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Full text of "Malacologia"

HARVARD UNIVERSITY 




LIBRARY 



OF THE 



Museum of Comparative Zoology 



VOL. 14 NO. 1-2 1973 



MALACOLOGIA 



PROCEEDINGS of the FOURTH 



EUROPEAN 



MALACOLOGICAL 



CONGRESS 



Geneva 1971 



v 



PROCEEDINGS 



of the 



FOURTH EUROPEAN MALACOLOGICAL CONGRESS 



(Geneva, 7-11 September 1971) 



Edited by Eugene E. BINDER 



Published by the Department of Invertebrates, 

Museum of Natural History, Geneva, Switzerland, 

and the Institute of Malacology, 

Ann Arbor, Michigan, U.S.A. 



Geneva, 1973 



(Price, US$ 25 or SFr. 80) 



mus. comp.îO° u 
LIBRARY 

AUG 3 1 1976 

HARVARD 

UNIVERS lTT - 



HONORARY COMMITTEE 



MM. W. DONZE, Président du Conseil d'Etat de Genève 

J. P. BUENSOD, Maire de la Ville de Genève 

A. CHA VANNE, Conseiller d'Etat 

Mme L. GIRARDIN, Conseiller administratif 

MM. Dr V. AELLEN, Directeur du Muséum 

Prof. Dr P. BROENNIMANN 

Prof. Dr M. FISCHBERG 

Prof. Dr H. J. HUGGEL 

Prof. A. JAYET 

Dr G. MERMOD 

Dr.E. BINDER 



ORGANIZING COMMITTEE 



Président: Dr E. BINDER 

Vice-Président: Dr F. E. LOOSJES 
Secrétaires: Dr D. RUNGGER 

Mlle M. T. MISSET 
Trêsorière: Mme Dr L. ZANINETTI 



PREFACE 

The present number is assigned to the Proceedings of the 4th European 
Malacological Congress, held in Geneva from September 7-11, 1971 under 
the sponsorship of UNITAS MALACOLOGICA EUROPAEA. Besides the papers 
delivered, it contains the report of the General Assembly of U.M.E. and also 
gives an account of some of the meetings the Congress has either sponsored 
or been host to, and which wished to see their decisions published. Discussion 
sessions on topics treated in the papers were well attended and stimulating, 
but the Congress's means did not permit a recording of the lively exchange 
of ideas, which will thus remain the sole benefit of the participants. 

The Congress Committee tender their thanks to all authors for their 
valuable contribution, to those members who acted as chairmen of communi- 
cation or discussion sessions, and to all those whose personal intervention 
contributed to the success of the undertaking. A special acknowledgement 
should be made to the memory of Professor A. Jayet, deceased shortly after 
Congress, who led the paleontological part of the excursion to the Jura. 

We are thankful to the Town authorities of Geneva and to the director of 
the Natural History Museum for placing the Museum's rooms and its per- 
sonnel at our disposal for the duration of Congress. 

The Congress is indebted to the State and to the Town of Geneva for the 
financial support of its meeting. The Swiss National Fund for Scientific 
Research* and the firm Hoffmann La Roche & Co. in Basle have generously 
contributed to the general expenses, and particularly to the publication costs 
of these proceedings. We also acknowledge the kind gestures made by the 
Société Française de Malacologie and by Dr. E. Loosjes in Wageningen«. 

Even with the aforementioned financial help, the publication of these pro- 
ceedings would not have been possible had it not been for the generous offer 
by Dr. J. B. Burch and the Institute of Malacology to have the proceedings 
published in their international review " Malacologia" , thus earning once 
again the gratitude of all the members and organizers of the Congress. 

E. BINDER 
(President) 



"Grant no. 3,444. 70 



CONTENTS 
FOURTH EUROPEAN MALACOLOGICAL CONGRESS 



Preface , щ 

Introduction 1 

Allocution présidentielle 3 

Presidential address, English summary . . . . „ 4 

Anrede des Vorsitzenden, Deutsche Zusammenfassung 5 

Report on the General Assembly of UNITAS MALACOLOGICAEUROPAEA 7 

Compte-rendu de l'Assemblée générale de l'U.M.E 9 

Bericht über die Generalversammlung der U.M.E 11 

Compte-rendu de la réunion de Faunistique continentale, le 10 septembre 1971. . . 13 

Working Conference on Distribution Mapping, September 10th, 1971 14 

Malacologists and the protection of Molluscs 15 

Resolution by UNITAS MALACOLOGICA EUROPAEA on the protection of Molluscs. . 16 

Paleontology 

ADEGOKE, O. S.: Paleocene Mollusks from Ewekoro, Southern Nigeria 19 

KROLOPP, E„: Faunengeschichtliche Bedeutung der altpleistozänen 

Molluskenfauna von Ungarn 29 

NORTON, P. E. P. & SPAINK, G.: The earliest occurrence of Macoma 

balthica (L) as a fossil in the North Sea deposit 33 

SPAINK, G.: Phylogenetical investigations in the Neogene Astartidae 

of the Southern North Sea basin (abstract) 38 

Shell structure and Ca secretion 

ADEGOKE, O. S.: Mineralogy and biogeochemistry of calcareous operculi 

and shells of some Gastropods 39 

VOVELLE, J.: Transfert du Calcium à travers l'épithélium du repli 

operculaire chez Astrea rugosa L. (Turbinidae) 47 

TIMMERMANS, L. P. M.: Mantle activity following shell injury in the 

pond snail Lymnaea stagnalis L 53 

Physiology and Endocrinology 

MORTON, В.: A new theory of feeding and digestion in the filter-feeding 

Lamellibranchia 63 

PRINSLOO, J. F. & VAN EEDEN, J. A.: The influence of temperature on 
the growth rate of Bulinus (Bulinus) tropicus (Krauss) and Lymnaea 
natalensis Krauss (Mollusca: Basommatophora) 81 

NEWELL, P. F. & SKELDING, J. M.: Studies on the permeability of the 

septate junction in the kidney of Helix pomatia L 89 

SKELDING, J. M.: Studies on the renal physiology of Achatina achatina (L.). ... 93 

OSBORNE, N. N.: Micro-biochemical and physiological studies on an 

identified serotonergic neuron in the snail Helix pomatia 97 

FOULQUIER, L., BOVARD, P. & GRAUBY, A.: Résultats expérimentaux sur la 
fixation du Zinc-65 par Anodonta cygnea (L) 107 

BORA Y, J. C: The role of the relative susceptibility of snails to infection with 
helminths and of the adaptation of the parasites in the epidemiology of some 
helminthic diseases 125 

TARDY, J.: Incidence de la castration chirurgicale sur le tractus génital et la 
ponte chez les Aeolidiidae: Application à la compréhension des mécanismes 
du contrôle endocrine de la sexualité 129 



PROC. FOURTH EUROP. MALAC. CONGR. 
CONTENTS (Continued) 

RUNHAM, N. W., BAILEY, T. G. & LARYEA, A. A.: Studies of the endocrine con- 
trol of the reproductive tract of the grey field slug Agriolimax reticulatus 135 

Structure 

RIGBY, J. E.: The anatomy of Cavolinia inflexa (Pteropoda) (abstract) 143 

ALLEN, J. A.: Functional morphology of the Verticordiidae (Bivalvia) 

(abstract) 143 

SOLEM, A.: Convergent evolution in Pulmonate radulae (abstract) 144 

THOMPSON, T. E. & BEBBINGTON, A.: Scanning electron microscope 

studies of Gastropod radulae . 147 

SCHELTEMA, A. H.: The radula of the Chaetodermatidae (Aplacophora, 

Chaetodermatida) (abstract) 166 

THOMPSON, T. E.: Euthyneuran and other molluscan spermatozoa 167 

SCHMEKEL, L.: Artcharakteristische Feinstrukturen bei Nudibranchiern 207 

Systematics of higher categories 

ROBERTSON, R. : The biology of the Architectonicidae, Gastropods combining 

Prosobranch and Opisthobranch traits 215 

BURCH, J. В.: A comparative study of some Polish and American 

Lymnaeidae: an assessment of phylogenetic characters (abstract) 221 

SMITH, B. J.: Problems of generic placement in Australian land molluscs 

(abstract) 222 

Systematics of species 

RUSSELL, P. J. C. & PETERSEN, G. H.: The use of ecological data in the 

elucidation of some shallow water European Cardium species. „ 223 

PETERSEN, G. H. & RUSSELL, P. J. C.:The nomenclature and classification 

of some European shallow-water Cardium species (abstract) 233 

DE ROOIJ-SCHUILING, L. A.: A preliminary report on systematics and 

distribution of the genus Ervilia Turton, 1822 (Mesodesmatidae, Bivalvia). . . 235 
STARMÜHLNER, F.: Die Gattung Me lanopsis Ferussac 1807 auf Neukaledonien. .242 

SABELLI, В.: On a Polyplacophora described by Monterosato (abstract) 244 

PARODIZ, J. J.: The species complex of Diplodon delodontus (Lam.) 

(Unionacea -Hyriidae) 247 

BOETERS, H. D.: Die Gattung Bythinella und die Gattung Marstoniopsis in 

Westeuropa, Westeuropäische Hydrobiidae, 4. (Prosobranchia) 271 

WIUM-ANDERSEN, G.: Electrophoresis as a support for the identification 

of various African Biomphalaria 287 

GIUSTI, F.: The minute shell structure of the glochidium of some species 

of the genera Unio, Potomida and Anodont a (Bivalvia, Unionacea) 291 

PEAKE, J. F.: Species isolation in sympatric populations of the genus 

Diplommatina (Gastropoda, Prosobranchia, Cyclophoridae, Diplommatininae). . 303 

Systematics: variability, polymorphism 

REAL, G.: Polymorphisme du test de Potamopyrgus jenkinsi (E. A. Smith, 

1889) en milieu saumâtre ou lacustre 313 

COOMANS, H. E.: Conidae with smooth and granulated shells 321 

GOODHART, С. В.: A 16-year survey of Cepaea on the Hundred Foot Bank. ... 327 
GUERRUCCI, M. A.: Aspects généraux du polymorphisme de la couleur du 

peristome chez les Cepaea hortensis en France 333 



PROC. FOURTH EUROP. MALAC. CONGR. 
CONTENTS (Continued) 

PETTITT, C: An examination of the distribution of shell pattern in Littorina 
saxatilis (Olivi) with particular regard to the possibility of visual selection 
in this species 339 

REX, M. A.: Prediction of the number of color morphs in populations 

of Liguus fasciatus (abstract) 344 

Ecology, Ecophysiology 

KLEEMANN, К.: Lithophaga lithophaga (L.) (Bivalvia) in different limestone. . . 345 
SAMPAIO XAVIER, M., DE AZEVEDO, J. F. & MATTOS DOS SANTOS, M.A.: 

Studies on the distribution and ecology of Lymnaea truncatula, intermediate 

host of Fasciola hepática in Portugal (abstract) . 348 

VAN DER SCHALIE, H. & BERRY, E. G.: The role of temperature in the 

ecology and distribution of the snail, Lymnaea stagnalis (abstract) 348 

BABA, К.: Wassermollusken-Zönosen in den Moorwäldern A Inion 

glutinosae (Malcuit) der Ungarischen Tiefebene 349 

CAMERON, R. A. D.: Some woodland mollusc faunas from Southern England. . . 355 
EDMUNDS, J. & EDMUNDS, M.: Preliminary report on the Mollusca of the 

benthic communities off Tema, Ghana 371 

TRUEMAN, E. R., BLATCHFORD, J. G., JONES, H. D. & LOWE, G. A.: 

Recordings of the heart rate and activity of molluscs in their natural habitat. . 377 
GARCIA, M. C: Recherches sur réchauffement de Cepaea nemoralis (L.) 

par l'énergie rayonnée 385 

CHATFIELD, J. E.: Aspects of feeding and growth in land snails 391 

IMHOF, G.: Der Einfluss von Temperatur und Photoperiode auf den 

Lebenszyklus einiger Süsswasserpulmonaten (abstract) 393 

MCDONALD, S, C: Activity patterns of Lymnaea stagnalis (L.) in relation 

to temperature conditions: a preliminary study (abstract) 395 

Biogeography 

SOLEM, A.: Island size and species diversity in Pacific Island land snails 397 

BARBOSA, F. S.: Possible competitive displacement and evidence of 

hybridization between two Brazilian species of planorbid snails 401 

SCHELTEMA, R. S.: Eastward and westward dispersal of tropical Prosobranch 

larvae across the Mid-Atlantic barrier (abstract) 409 

VALOVIRTA, I. : The distribution of the land molluscs in the upheaval area 

in the Quarken, an archipelago in the Gulf of Bothnia (summary) 409 

Zoogeography 

HEATH, J.: The European Invertebrate survey 411 

ANT, H.: Vorschläge zur Erfassung der mitteleuropäischen Mollusken 

(Zusammenfassung) „ . . . . 414 

JA YET, A.: Sur quelques Pisidiums haut-alpins 415 

VAN BRUGGEN, А. С: Distribution patterns of the genus Gulella (Gastropoda 

pulmonata: Streptaxidae) in Southern Africa 419 

GITTENBERGER, E.: Die Formen von Abida sécale (Draparnaud) in den 

östlichen Pyrenäen (Zusammenfassung) 426 

MORRISON, J. P. E.: Zoogeography of the pleurocerine fresh water snails 

(abstract) 426 

MEAD, A. R.: A prognosis in the spread of the giant African snail to 

continental United States (abstract) 427 



PROC. FOURTH EUROP. MALAC. CONGR. 
CONTENTS (Continued) 

SALVAT, В.: Mollusques des îles Tubuai (Australes, Polynésie) Comparaisons 
avec les îles de la Société et des Tuamotu . 429 

KNUDSEN, J.: Some aspects of the distribution of the marine molluscs of 

West Africa (abstract) 431 

PANETTA, P.: Les mollusques bathyals du Golfe de Tarente (résumé) 432 

Miscellaneous 

CHAIX, L.: Quelques cas de diphyoidie observés sur des Mollusques 

continentaux * . . 433 

OBERLING, J. J.: Notes on the ornamentation of mollusk shells (abstract) 438 

DEMIAN, E. S. & KAMEL, E. G.: Effect of Marisa cornuarietis on Bulinus 

truncatus populations under semi-field conditions in Egypt (abstract) 439 

GODAN, D.: Die ökologischen Grundlagen der Prüfungsmethoden von 

Molluskiziden (Zusammenfassung) 439 

KO BUN HIAN: A new injection fluid for malacologists (summary) 440 

DEXTER, R. W.: Historical aspects of Alpheus Hyatt's work on fossil 

Cephalopods (summary) 441 

Exhibits 445 

List of Congress members 447 

Index 453 






MALACOLOGIA, 1973, 14: 1-16 

PROC. FOURTH EUROP. MA LAC. CONGR. 



INTRODUCTION 

The 4th European Malacological Congress, sponsored by UNITAS MALACOLOGICA 
EUROPAEA (U.M.E.), took place in Geneva at the Museum of Natural History from 
September 7 to 11, 1971, hosted by Dr. E. Binder, president of the UNITAS. One 
hundred and sixty-seven malacologists participated, coming from 26 countries s in- 
cluding 10 outside Europe. 

The Congress proper was preceded by a 1-day meeting of museum curators in 
charge of mollusc collections. The Congress was also host to working conferences 
of council members of malacological societies, and of directors of malacological 
reviews. The European Invertebrate Survey and the Commission Faunistique Conti- 
nentale de la Société Française de Malacologie held a joint meeting to set up a common 
program of work and to unify their methods of mapping. A discussion meeting was 
held on the possible role of malacologists in the protection of molluscs, which brought 
forth a draft resolution submitted to U.M.E. The General Assembly of U.M.E. closed 
the working part of the Congress, as usual. 

The opening session of the Congress was honoured by the presence of representa- 
tives of the State and of the City of Geneva: Monsieur le Conseiller d'Etat André 
Chavarme, chargé du Département de l'Instruction Publique, and Madame le Con- 
seiller Administratif Lise Girardin, Délégué aux Beaux-Artsetà la Culture. Conseil- 
ler Chavarme welcomed the Congress on behalf of both State and City authorities. 
The President, Dr. E. Binder, after delivering his address, and representing the 
Museum Director, Dr. W. Aellen, expressed his pleasure at receiving the Congress 
in the new Museum building and his wishes for a fruitful and agreeable session. 

During the Congress, a special room was reserved for exhibits of material or 
figures and photographs by Congress members. Two invited lectures were given, 
one by Dr. K. J. Boss, on the number of mollusc species, the other by Dr. W. Streiff 
on molluscan endocrinology. A half -day boat tour was organized on Lake Geneva, and 
a whole day excursion led the participants to a variety of paleontological and ecologi- 
cal stations ranging from the foot of the Jura to the Col du Marchairuz and to Lac de 
Joux. 

All those taking part in the Congress were invited to a cocktail party at the Hotel 
Métropole on the first day by the authorities of the State and City of Geneva. At the 
end of the Congress, a closing dinner was given at the Airport Restaurant; these occa- 
sions were welcome opportunities for renewed personal contact. 



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PROC. FOURTH EUROP. MALAC. CONGR. 
ALLOCUTION PRESIDENTIELLE 
Mesdames et Messieurs, 

Pour la quatrième fois, les malacologues d'Europe et d'ailleurs se réunissent sous 
les auspices de l'UNITAS MALACOLOGICA EUROPAEA. Au nom de l'UNITAS, je 
vous souhaite la bienvenue à ce Congrès. Je suis heureux de constater que vous êtes 
venus nombreux, ce qui témoigne du développement et du rayonnement de l'UNITAS. 
Je tiens à saluer particulièrement ceux d'entre vous qui sont venus de loin et qui ont 
dû entreprendre un déplacement important et parfois de longues formalités pour se 
joindre à nous pendant ces quelques jours. 

La composition du congrès est harmonieusement équilibrée cette année par un 
important contingent de malacologues français. Ceci n'est pas dû uniquement à la 
proximité de la France mais surtout à la fondation, depuis le dernier congrès, de la 
Société Française de Malacologie qui est en rapport étroit avec l'UNITAS et qui était 
d'ailleurs en gestation lors du congrès de Vienne en 1968. Son président, son secré- 
taire, son trésorier et plusieurs membres du conseil sont membres de l'UNITAS et 
se trouvent parmi nous aujourd'hui. Cette jeune société comptait déjà au bout d'un 
an plus d'une centaine de membres et elle a déjà tenu son premier congrès à Caen, 
il y a exactement une année. Elle publie le périodique "Haliotis". Un autre événement 
heureux du même ordre est la fondation de la Société Malacologique Israélienne, 
animée par notre collègue Mienis. Cette société, elle aussi, a déjà organisé un colloque 
et elle a sa publication, intitulée "Argamon". A l'opposé de ces sociétés nouvelles, 
la Deutsche Malakozoologische Gesellschaft a fêté son centième anniversaire, ce dont 
nous avons déjà eu le plaisir de la féliciter. 

Nouvelles sociétés malacologiques, anciennes sociétés malacologiques toujours 
jeunes et vivaces, c'est ainsi que se manifeste la vitalité de la recherche dans notre 
domaine. Si l'UNITAS peut se flatter d'avoir influencé dans une certaine mesure la 
vie des sociétés nationales, cette influence a été réciproque: La Société Française 
de Malacologie a collaboré de façon très positive en apportant une aide financière à 
ce congrès, où elle s'est fait officiellement représenter, et en prenant l'initiative 
d'un essai de coordination des comités des sociétés malacologiques. La Société 
Malacologique Italienne a proposé un candidat à la présidence de l'Unitas, ainsi que 
le lieu du prochain congrès. Les sociétés néerlandaise, française et allemande ont 
présenté des candidats au poste de vice-président. Il est d'ailleurs souhaitable 
d'améliorer la coordination entre les diverses sociétés malacologiques, et l'UNITAS 
devrait pouvoir jouer un rôle central. Une réunion des membres des conseils de 
sociétés malacologiques et de l'UNITAS aura lieu dans ce but au cours de ce congrès. 

Beaucoup d'aspects du présent congrès sont les résultats de décisions prises, de 
voeux exprimés lors du dernier congrès ou d'influences, de tendances manifestées 
depuis lors. Ainsi nous avons réalisé une des suggestions faites par notre prédéces- 
seur, de réunir en marge du congrès les conservateurs de musées chargés des col- 
lections de Mollusques. Cette réunion a eu lieu hier, elle a compté une quarantaine 
de participants et je crois pouvoir dire qu'elle fut à la fois longue, fertile et agréable. 
Quant au congrès lui-même, sa forme répond à un désir généralement exprimé de ne 
pas comprendre plusieurs sections parallèles, afin de permettre à chaque congressiste 
d'entendre toutes les communications qui l'intéressent. Cela implique évidemment un 
temps de parole fort court et nécessitera une certaine discipline de la part des orateurs 
- et sans doute aussi une certaine fermeté de la part des présidents de séances - mais 
cette forme n'a rien d'exceptionnel, elle est de plus en plus adoptée dans la plupart 

(3) 



4 PROC. FOURTH EUROP. MALAC. CONGR. 

des congrès, et je pense que vous n'aurez pas de peine à vous y plier. Afin de remé- 
dier à son principal inconvénient qui est l'impossibilité de discuter longuement 
après chaque communication, des séances de discussion ont été prévues à d'autres 
moments, principalement pendant les soirées, et grouperont chacune les personnes 
qui s'intéressent à un sujet; au cours de ces séances des questions pourront être 
posées aux auteurs de communications, mais la conversation pourra aussi prendre 
un tour plus général sans trop de restriction de sujet ni de temps. Les présidents des 
séances de discussion auront toute latitude de les organiser et de les diriger. Cette 
partie de notre activité pourrait bien se révéler l'une des plus intéressantes. 

En parcourant vos programmes, vous avez pu constater que les sujets traités dans 
les nombreux travaux présentés sont très variés et que les domaines sont bien équili- 
brés; la physiologie est beaucoup mieux représentée que dans les congrès précédents; 
seule la paléontologie est peu traitée. En ce qui concerne les conférences principales, 
l'une (Boss) est un sujet de systématique très général, l'autre (Streiff) traite d'un 
aspect de la physiologie des Mollusques qui a des incidences dans tous les autres 
domaines. L'excursion au Jura montrera aux paléontologues les formes fossiles 
quaternaires de la craie lacustre et des tufs de la Combaz, tandis que les écologistes 
pourront constater les changements de peuplement avec l'altitude, l'exposition et le 
substrat. Ainsi, je pense que tous les goûts seront satisfaits et j'espère qu'avec 
votre contribution le congrès qui s'ouvre sera un succès dans son genre. 

PRESIDENTIAL ADDRESS - ENGLISH SUMMARY 

Ladies and Gentlemen, 

Welcome to the IV. European Malacological Congress. Our meeting is honoured by 
the presence of representatives of the State and City of Geneva: M. le Conseiller 
d'Etat Chavanne et Mme le Conseiller Administratif Girardin. Several other organi- 
zations are also officially represented at the Congress. 

The number of congressists is a reflection of the development and growing influence 
of UNITAS. One hundred and seventy-four participants have registered, coming from 
31 countries. I greet especially those who come from other continents. 

Since the last congress, the following well-known malacologists are deceased: Prof. 
Fritz Haas of Chicago, Prof. Siegfried Jaeckel of Berlin, and Prof. Gunnar Thorson 
of Helsing0r. 

This year, the composition of our assembly is well balanced by the presence, for 
the first time, of an important French participation. This is due to the recent founda- 
tion of the Société Française de Malacologie (S. F. M.), which is closely linked with 
the Unitas and brings us in contact with the French malacologists. This new French 
society has developed quickly and has already held a congress in September 1970. It 
issues a new publication called "Haliotis". Another malacological society has been 
founded: the Israelian Malacological Society, which also has already held a colloquium 
and has its own review "Argamon". We greet the birth of these new societies and 
wish them a long and fruitful development, following the example of the Deutsche 
Malakologische Gesellschaft, which has celebrated in 1969 its 100th year of existence. 
These events show the lively expansion of malacological research. 

Cooperation by the different malacological societies with the UNITAS is active and 
satisfactory: The Société Française de Malacologie has contributed materially to the 
present Congress. The Società Malacologica Italiana has proposed a place for the next 
congress; the 3 Italian, Dutch and German societies have nominated candidates for 
our next council of the UNITAS MALACOLOGICA EUROPAEA. 

We feel the need to improve the coordination between the Councils of the main 



BINDER: ALLOCUTION PRESIDENTIELLE 5 

malacological societies, and UNITAS ought to play an important part in this effort. 
This is the reason for a meeting of the Council members of malacological societies 
during this congress. 

Another meeting in connection with the Congress is the one of museum curators in 
charge of mollusc collections, which took place yesterday and which I think I may say 
has been pleasant and fruitful. The Continental Faunistic Commission of the S.F.M. 
will take advantage of the Congress to hold a meeting, and so will the directors of 
malacological reviews. 

It is the duty of UNITAS to make a stand against any action which spoils the environ- 
ment, and especially against over-collecting of molluscs (see fly-leaf entitled "Mala- 
cologists and the protection of molluscs"). 

The Congress itself will not comprise several parallel sections, so that every parti- 
cipant will be able to attend all the lectures which interest him. This implies a rather 
short time for speeches, and will require some discipline on the part of the speakers, 
but this is the way things are in most congresses. To avoid the main drawback, i.e., 
the fact that it is impossible to discuss each lecture within speaking time, discussion 
sessions have been provided at a later moment; they will bring together people inter- 
ested in each particular subject; the speakers can then be asked questions and the 
resulting talks can extend to more general considerations without being restricted 
too much as regards topics or time. The chairmen will be given great liberty in 
organizing and leading these discussions according to their judgement. 

Besides the lectures, a few scientific exhibits from participants are being displayed 
in the Museum. 

The subjects dealt with by the lecturers are varied and rather well-balanced. Only 
in paleontology are there rather few lectures. One of the main conferences deals 
with systematics and the other with physiology. On the other hand, the excursion in 
the Jura will interest paleontologists and ecologists. So we expect that all kinds of 
interests will be satisfied and hope that, with your active participation, this Congress 
will be a success. 

ANREDE DES VORSITZENDEN - DEUTSCHE ZUSAMMENFASSUNG 

Meine Damen und Herren, 

Seien Sie willkommen zum IV. Europäischen Malakologen-Kongress. Wir haben die 
Ehre, die Anwesenheit von Vertretern des Staats und der Stadt Genf zu begrüssen, 
nämlich M. le Conseiller d'Etat Chavanne und Mme le Conseiller Administratif 
Girardin. Auch verschiedene andere Organisationen sind hier offiziell vertreten. 

Die Zahl der Kongressisten zeigt Entwicklung und Ausstrahlen der UNITAS. Es 
haben sich 174 Teilnehmer angemeldet, die von 31 Ländern kommen. Ich möchte 
hier besonders diejenigen begrüssen, die von anderen Kontinenten kommen. 

Seit dem letzten Kongress sind folgende bekannte Malakologen gestorben: Prof. 
Fritz Haas, von Chicago, Prof. Siegfried Jaeckel, von Berlin, und Prof. Gunnar Thor- 
son, von Helsing0r. 

Dieses Jahr erfreuen wir uns der Teilnahme einer bedeutenden französischen 
Delegation. Dies verdanken wir der vor einiger Zeit erfolgten Gründung der Société 
Française de Malacologie (S. F. M.), welche mit der UNITAS enge Beziehungen pflegt 
und uns somit mit unseren französischen Kollegen in Verbindung setzt. Diese neue 
französische Gesellschaft hat sich rasch entwickelt und hat bereits im September 
1970 einen Kongress abgehalten. Sie veröffentlicht eine Zeitschrift unter dem Titel 
"Haliotis". Es wurde noch eine andere malakologische Gesellschaft gegründet, die 
Israelian Malacological Society, die schon ein Kolloquium abgehalten hat und ein 



6 PROC. FOURTH EUROP. MALAC. CONGR. 

Blatt "Argamon" erscheinen lässt. Wir begrüssen die Gründung dieser neuen Ge- 
sellschaften und wünschen ihnen eine lange und fruchtbare Laufbahn, wie zum Beispiel 
diejenige der Deutschen Malakologischen Gesellschaft, welche im 1969 ihren hundertsten 
Jahrestag feierte. Diese Ereignisse beweisen die lebhafte Entwicklung der malakolo- 
gischen Forschung. 

Es besteht zwischen den verschiedenen malakologischen Gesellschaften und der 
UNITAS eine rege und erfreuliche Mitarbeit: Die Société Française de Malacologie 
hat dem heutigen Kongress finanziell beigetragen. DieSocietaMalacologica Italiana 
hat vorgeschlagen, den nächsten Kongress in Italien zu beherbergen. Die italienische, 
die holländische und die deutsche Gesellschaften haben für den nächsten Vorstand 
der UNITAS MALACOLOGICA EUROPAEA Kandidaten angemeldet. 

Es scheint nötig, dass die Mitarbeit zwischen den Vorständen der wichtigsten mala- 
kologischen Gesellschaften verstärkt wird, und wir glauben, dass die UNITAS hier 
eine führende Rolle spielen könnte. Deshalb ist im Laufe dieses Kongresses eine 
Zusammenkunft der Vorstandsmitglieder der malakologischen Gesellschaften vor- 
gesehen. 

Im Zusammenhang mit dem Kongress wurde gestern eine Sitzung von den mit der 
Verwaltung von Molluskensammlungen beauftragten Museumskustoden abgehalten, von 
der ich glaube, sagen zu dürfen, dass sie angenehm und fruchtbar gewesen ist. 

Die Kontinentale faunistische Kommission der S.F.M. wird die Gelegenheit des Kon- 
gresses benutzen, um eine Sitzung abzuhalten, und ebenso die Direktoren der mala- 
kologischen Zeitschriften. 

Es ist eine Pflicht für die UNITAS, gegen alles, was die natürliche Umgebung 
zerstört, Stellung zu nehmen, und insbesondere gegen die übermässige Aufsammlung 
von Mollusken (siehe Separat-Blatt unter dem Titel "Die Malakologen und der Mol- 
lusken-Schutz"). 

Der Kongress selber ist nicht in verschiedenen parallelen Sektionen eingeteilt, 
damit jeder Teilnehmer alle ihn interessierenden Vorträge hören kann. Das bedingt 
eine ziemlich kurze Sprechzeit und wird den Rednern eine gewisse Disziplin auferlegen, 
aber das ist wohl der Fall in den meisten Kongressen. Um den grössten Nachteil, 
nämlich die Unmöglichkeit einer Diskussion gleich nach dem Vortrag, vorzubeugen, 
wurden Diskussions-Sitzungen auf einen späteren Zeitpunkt festgesetzt. Dann können 
die Leute, die für ein besonderes Thema gemeinsam Interesse haben, dem Redner 
Fragen stellen, was eine Erweiterung der Diskussion auf einer breiteren Basis, ohne 
allzugrosse Objekt- oder Zeiteinschränkung, ermöglichen wird. Es wird dem Vor- 
sitzenden überlassen, die Diskussion nach seinem Gutdünken zu organisieren und zu 
führen. 

Ausser den Vorträgen werden im Museum einige wissenschaftliche Demonstrationen 
von Teilnehmern vorgezeigt. 

Die von den Rednern vorgebrachten Themen sind mannigfaltig und ziemlich gut 
verteilt. Allein in der Paläontologie gibt es nur wenig Vorträge. Der erste Haupt- 
vortrag bezieht sich auf Systematik und der zweite auf Physiologie. Andrerseits 
wird der Jura-Ausflug für Paläontologen und Oekologen besonders Interesse bieten. 
Wir glauben somit den verschiedenen Interessen eines jeden Teilnehmers zu ent- 
sprechen und hoffen, dass dank Ihrer aktiven Anteilnahme unser Kongress erfolgreich 
verlaufen wird. 

E. BINDER 



PROC. FOURTH EUROP. MALAC CONGR. 

PROCEEDINGS OF THE GENERAL ASSEMBLY OF 
UNITAS MALACOLOGICA EUROPAEA 

by the Secretary, Dr. A. Zilch 

The 1971 meeting of the General Assembly of UNITAS MALACOLOGICA EUROPAEA 
took place at the Geneva Natural History Museum on Saturday, September 11, at 
5:00 p.m. We again thank Mr. G. I. Crawford for being the Chairman. 

The assembly followed the order of the agenda which had been mailed to all members 
on June 9, 1971, in accordance with paragraph 8 of the Rules of UNITAS. 

1. Confirmation of new members 

The new members of UNITAS as shown in an appendix to the agenda were confirmed. 

2. Report by the President on UNITAS' work 

Dr. Binder, the President, presented a report on the work of UNITAS since the last 
General Assembly. 

In November 1969, the "Proceedings of the Third European Malacological Congress, 
Vienna 1968" were published by the Department of Mollusks of the Vienna Natural 
History Museum and the Institute of Malacology, Ann Arbor, as vol. 9 no. 1 of "Mala- 
cologia". Copies were sent to all participants of the Congress and to all other members 
of UNITAS. 

Four members of the Council of UNITAS met in Frankfurt am Main on May 24, 
1969, for a first discussion of the preparation of the Geneva Congress. A meeting of 
all members of the Council took place in Basle on December 19, 1970. Dr. Binder 
reported on the subjects discussed in these meetings and pertaining to the general 
policy of UNITAS, especially on the matters of eventual honorary members, of ad- 
mission conditions of new members and on the position of UNITAS concerning the 
protection of mollusks (see point 9 of this report). 

Up to the date of the General Assembly, 27 new members joined UNITAS. Three 
members died (H. Modell in 1969, Dr. F. Haas in 1969, Prof. Dr. G. Thorson in 1971). 
Five members resigned, and one membership was cancelled. Thus, the number of 
members increased from 139 l on September 6, 1968, to 157 on September 11, 1971. 

The 157 members consisted of: 

Ordinary members (personal 121, collective 10). , .... 131 

Corresponding members (all personal) « 26 

They came from 30 countries: 

a) Ordinary members in 20 countries: 

Austria (2), Belgium (2), Denmark (6), Egypt (1), France (22), Germany (12), 
Great Britain (20), Hungary (2), Israel (2), Italy (13), Morocco (2), Netherlands 
(21), Norway (3), Poland (1), Portugal (4), Rumania (2), Sweden (4), Switzerland 
(8), Turkey (2), Yugoslavia (2). 

b) Corresponding members in 9 countries: 

Australia (2), Brazil (1), Canada (1), Ethiopia (1), Ghana (1), New Zealand (1), 
Nigeria (2), South Africa (1), U.S.A. (16). 



4n "Malacologia", 9(1): 17, the number 140 was published; one ordinary personal member who 
had applied for membership at the assembly did not confirm his application in writing. 

(V) 



8 PROC. FOURTH EUROP. MALAC. CONGR. 

3. Statement of accounts by the Treasurer 

Dr. Forcart, the Treasurer, presented the following statement of accounts (in Swiss 
Francs) for the period from August 9, 1968, to August 26, 1971. The statement had 
been audited by Dr. Toffoletto and, in absence of Mr. Dance, by Mr. Girod. 

S. Fr. 

Income 6,742.08 

Expenditure 5,037.70 

Excess of Income . . . . . 1,704.38 

Assets Schweizerischer Bankverein (E.H. 941085) 7,020.12 

Balance 8.8.1968 5,315.74 

Balance 26.8.1971 7,020.12 

Excess 1,704.38 

4. Approval of acts of councillors 

The acts of the councillors for the period from 1968 to 1971 were approved. 

5. Postal ballot on new councillors for the period 1971-1974 

Three statutory proposals had been received by the Secretary for the election of 
the new Council. These were submitted by the Società Malacologica Italiana, the 
Nederlandse Malacologische Vereniging, and the Deutsche Malakozoologische Ge- 
sellschaft. The Council of UNITAS agreed to these proposals. They were mailed as 
a ballot to all 121 ordinary personal members on July 21 and 22, 1971, in accordance 
with paragraph 11 of the Rules. At the General Assembly the following result of the 
voting in which only 63 2 members had participated was announced: 

President: 

Dr. F. Toffoletto, Italy 
Vice President: 

Dr. B. Salvat, France 

Dr. A. C. van Bruggen, Netherlands 
Secretary: 

Dr. O. E. Paget, Austria 62 

Treasurer: 

Dr. P. Jung, Switzerland 60 

Member of Council: 

J. F. Peake, B.Sc, England 59 

Thus, the following office holders were elected members of Council: 

President: Dr. F. Toffoletto (Milan, Italy) 

Vice President: Dr. A. C. van Bruggen (Leiden, Netherlands) 

Secretary: Dr. O. E. Paget (Vienna, Austria) 

Treasurer: Dr. P. Jung (Basle, Switzerland) 

Member of Council: J. F. Peake, B.Sc. (London, England) 



yes 


no 


abstention 


62 


- 


1 


(16+) 3 19 
(16+) 3 27 


2 
5 


2 
2 



^4 voting papers were mailed too late and reached the Secretary only after the date of the Gener- 
al Assembly. 

ЗОп 16 voting papers both nominations for the office of the Vice President were marked with a 
cross. 






PROC. FOURTH EUROP. MALAC. CONGR. 9 

6. Election of auditors for the period 1971-1974 

The following members were appointed auditors: Mr. J. M. Gaillard, Paris, and Mr. 
A. Girod, Milan. 

7. Subscription for the period 1971-1974 

The annual subscription rates of 10.00 Swiss Francs for ordinary members and 
5.00 Swiss Francs for corresponding members were not altered. 

8. Year and place of the next Congress 

The President-Elect, Dr. Toffoletto, invited the members of UNITAS to the next 
Congress in Milan in 1974. The invitation was accepted. 

9. Other business 

a) List of Malacologists and Bibliography: 

At the last General Assembly in 1968, Dr. Paget had been authorized to make 
further efforts at completing the projects as mentioned under numbers 2, 4, and 5 in 
the Resume of the Presidential Address published in the Proceedings of the Third 
European Malacological Congress p 14. In the meantime the "List of European Mala- 
cologists 197 1" has been published and can be obtained from Dr. Oliver Paget, Natur - 
historisches Museum, Burgring 7, A-1014 Wien, Austria (price: 5 international reply 
coupons). Bibliographies for the years 1969 and 1970 are also obtainable, free of 
charge. The 1971 bibliography is being prepared. The project foreseen under No. 5 
is underway and results shall be published in due time. 

b) Protection of Mollusks: 

The draft resolution submitted by the drafting commission was discussed and 
unanimously adopted after some minor changes. (See page 16.) 

COMPTE RENDU DE L'ASSEMBLEE GENERALE DE 
L'UNITAS MALACOLOGICA EUROPAEA 

par le Secrétaire, Dr. A. Zilch 

L'Assemblée générale de 1971 de l'UNITAS MALACOLOGICA EUROPAEA s'est 
tenue à Genève, au Muséum d'Histoire Naturelle, le samedi 11 septembre à 17 h. Nous 
remercions M. G. I. Crawford d'avoir bien voulu en assumer la présidence. 

L'assemblée s'est déroulée conformément à l'ordre du jour qui avait été envoyé à 
tous les membres le 9 juin 1971 en application de l'art. 8 des statuts de l'UNITAS. 

1. Confirmation de nouveaux membres 

L'admission des nouveaux membres, dont la liste était annexée à l'ordre du jour, a 
été confirmée. 

2. Rapport du Président sur l'activité de l'UNITAS 

Le Président, Dr. Binder, a présenté son rapport sur l'activité de l'UNITAS depuis 
la dernière assemblée générale. 

Les "Proceedings of the Third European Malacological Congress, Vienna 1968" 
ont été publiés en novembre 1969 par le Département des Mollusques du Musée 
d'Histoire Naturelle de Vienne et par l'Institute of Malacology, Ann Arbor, comme 
vol. 9 No. 1 de "Malacologia". Tous les participants au Congrès et tous les autres 
membres de l'UNITAS en ont reçu un exemplaire. 

Quatre membres du Conseil de l'UNITAS se sont réunis le 24 mai 1969 à 
Francfort sur le Main pour une première discussion sur la préparation du Congrès 



10 PROC. FOURTH EUROP. MALAC. CONGR. 

de Genève. Puis tous les membres du Conseil ont tenu séance à Bâle le 19 décembre 
1970. Le Dr. Binder rappela les principaux sujets discutés au cours de ces séances 
et concernant la politique générale de l'UME, notamment la question d'éventuels 
membres honoraires, les modalités d'admission des nouveaux membres et l'attitude 
de l'UME face au problème de la protection des Mollusques (voir point 9 de l'ordre 
du jour). 

27 nouveaux membres ont adhéré à l'UNITAS en cours d'exercice. Trois membres 
sont décèdes (H. Modell en 1969, Dr. F. Haas en 1969, Prof. Dr. G. Thorson en 1971). 
Cinq membres ont démissionné et un fut exclu. Ainsi, le nombre des membres a 
passé de 139 1 le 6 septembre 1968 à 157 le 11 septembre 1971. Ce chiffre de 157 
comprenait: 

Membres ordinaires (individuels 121, collectifs 10) 131 

Membres correspondants (tous individuels) 26 

(Pour la répartition par pays, se référer à la version anglaise) 

3. Présentation des comptes par le Trésorier 

Le Trésorier, Dr. Forcart, présenta les comptes (établis en francs suisses) pour 
la période allant du 9 août 1968 au 26 août 1971. Ces comptes avaient été vérifiés 
par le Dr. Toffoletto et, en l'absence de Mr. Dance, par M. Girod. 
(Pour le relevé de compte, voir la version anglaise) 

4. Décharge au Comité 

Décharge fut donnée au Comité pour sa gestion pendant la période de 1968 à 1971. 

5. Election du nouveau Comité pour la période 1971-1974 

Pour l'élection du nouveau Comité, le Secrétaire a reçu trois propositions statutaires, 
soumises respectivement par la Société Malacologique Italienne, la Société Malacolo- 
gique Néerlandaise et la Société Malacologique Allemande. Le Comité de l'UNITAS a 
approuvé ces propositions. Elles furent soumises par poste aux 121 membres indi- 
viduels ordinaires les 21 et 22 juillet 1971, conformément à l'art. 11 des statuts. Le 
résultat de la votation, à laquelle 63 2 membres seulement avaient participé, fut 
proclamé à l'assemblée générale. 
(Pour le détail, se référer à la version anglaise) 

6. Election des vérificateurs des comptes pour la période 1971-1974 

Les membres suivants ont été désignés comme vérificateurs des comptes: M. J. M. 
Gaillard, Paris, et M. A. Girod, Milan. 

7. Cotisations pour la période de 1971 à 1974 

Les cotisations actuelles de 10 francs suisses par an pour les membres ordinaires 
et de 5 francs suisses par an pour les membres correspondants ont été maintenues. 

8. Date et lieu du prochain Congrès 

Le Président élu, Dr. Toffoletto, invita les membres de l'UNITAS à venir à Milan 
pour le prochain Congrès en 1974, invitation qui fut acceptée. 



^•Le vol. 9(1) de "Malacologia" indiquait, en page 17, le nombre de 140; un membre ordinaire 
individuel qui avait demandé son admission lors de l'assemblée, n'a pas confirmé sa demande 
par écrit. 

24 bulletins de vote expédiés trop tard n'ont atteint le Secrétaire qu'après la date de l'assemblée 
générale. 



PROC. FOURTH EUROP. MALAC. CONGR. И 



9. Divers 

a) Liste des Malacologues et bibliographie: 

A la dernière assemblée générale en 1968, le Dr. Paget avait été chargé de 
poursuivre la réalisation des projets indiqués sous 2, 4 et 5 dans le Résumé du Dis- 
cours présidentiel (Proc. Third Europ. Malac. Congr., p 14). La "Liste des Mala- 
cologues européens 1971" a été publiée dans l'intervalle. Elle peut être obtenue 
auprès du Dr. Oliver Paget, Naturhistorisches Museum, Burgring 7, A-1014 Wien, 
Oesterreich (5 coupons-réponse internationaux). Les bibliographies pour les années 
1969 et 1970 (littérature européenne seulement) sont également disponibles, gratuite- 
ment. La bibliographie pour 1971 est en préparation. On continue à s'occuper du 
projet mentionné sous chiffre 5; les résultats seront publiés en temps utile. 

b) Protection des Mollusques: 

Le projet de résolution soumis par la commission de rédaction ad hoc a été 
discuté et adopté à l'unanimité après modifications. (Voir page 16.) 

BERICHT ÜBER DIE GENERALVERSAMMLUNG DER 
UNITAS MALACOLOGICA EUROPAEA 

vom Sekretär, Dr. A. Zilch 

Die Generalversammlung 1971 der UNITAS MALACOLOGICA EUROPAEA fand am 
Samstag, dem 11. September, um 17 Uhr im Naturhistorischen Museum der Stadt 
Genf statt. Wir danken Herrn G. I. Crawford, dass er wieder das Amt des Chairman 
übernommen hat. 

Die Versammlung folgte der Tagesordnung, die am 9. Juni 1971, gemäss § 8 der 
Satzung der UNITAS, an alle Mitglieder verschickt worden war. 

1. Bestätigung neuer Mitglieder 

Die neuen Mitglieder der UNITAS (Anlage der Tagesordnung) wurden bestätigt. 

2. Tätigkeitsbericht des Präsidenten 

Der Präsident, Dr. Binder, gab einen Bericht über die Tätigkeit der UNITAS seit 
der letzten Generalversammlung. 

Im November 1969 sind die "Proceedings of the Third European Malacological 
Congress, Vienna 1968" als Band 9 Nummer 1 der "Malacologia" von der Mollusken- 
Sektion des Naturhistorischen Museums Wien und dem Institute of Malacology, Ann 
Arbor, veröffentlicht worden. Jeder Kongressteilnehmer und jedes weitere Mitglied 
der UNITAS hat ein Exemplar erhalten. 

Diejenigen Vorstandsmitglieder der UNITAS, die zur Feier des 100jährigen Be- 
stehens der Deutschen Malakozoologischen Gesellschaft in Frankfurt am Main anwesend 
waren, sind am 24. Mai 1969 zu einer ersten Besprechung der Vorbereitungen des 
Genfer Kongresses zusammengekommen. Eine Sitzung aller Vorstandsmitglieder hat 
am 19. Dezember 1970 in Basel stattgefunden. Dr. Binder berichtete über die be- 
sonderen Punkte, die auf dieser Sitzung erörtert worden sind, vor allem das Problem 
des Molluskenschutzes. 

Bis zum Zeitpunkt der Generalversammlung sind der UNITAS 27 neue Mitglieder 
beigetreten. Drei Mitglieder sind verstorben (H. Modell 1969, Dr. F. Haas 1969, 
Prof. Dr. G. Thorson 1971). Fünf Mitglieder haben ihren Austritt erklärt, und ein 
Mitglied wurde gestrichen. Dadurch ist die Zahl der Mitglieder von 139 1 am 6. 



1 In "Malacologia", 9(1): 17 ist die Zahl 140 veröffentlicht worden; ein persönliches ordentliches 
Mitglied, das sich auf der Versammlung um die Mitgliedschaft beworben hatte, hat trotz mehr- 
facher Aufforderung eine schriftliche Beitrittserklärung nicht abgegeben. 



12 PROC. FOURTH EUROP. MALAC. CONGR. 

September 1968 auf 157 am 11. September 1971 angewachsen. 
(Vgl. die Zusammenstellung in der englischen Fassung.) 

3. Vorlage des Rechnungsabschlusses durch den Schatzmeister 

Der Schatzmeister, Dr. Forcart, gab eine Übersicht über die finanziellen Verhält- 
nisse der UNITAS für die Zeit vom 9. August 1968 bis zum 26. August 1971. Die 
Rechnungsführung ist von Herrn Dr. Toffoletto und, in Abwesenheit von Herrn Dance, 
von Herrn Girod geprüft worden. 
(Vgl. die Zusammenstellung in der englischen Fassung.) 

4. Entlastung des Vorstandes 

Der Vorstand (1968-1971) wurde entlastet. 

5. Wahl des neuen Vorstandes für die Periode 1971-1974 

Für die Wahl des neuen Vorstandes sind drei satzungsgemässe Vorschläge beim 
Sekretär eingegangen, die von der Società Malacologica Italiana, der Nederlandse 
Malacologische Vereniging und der Deutschen Malakozoologischen Gesellschaft ein- 
gereicht wurden. Der Vorstand der UNITAS hat sich diesen Vorschlägen angeschlossen. 
Die Stimmzettel sind am 21. und 22. Juli 1971, gemäss § 11 der Satzung, an alle 121 
persönlichen ordentlichen Mitglieder abgeschickt worden. Auf der Generalversammlung 
wurde das Ergebnis der Wahl, an der sich nur 63 2 Mitglieder beteiligt haben, be- 
kanntgegeben und damit der neue Vorstand der UNITAS gewählt. 
(Vgl. die Zusammenstellung in der englischen Fassung.) 

6. Wahl der Rechnungsprüfer für die Periode 1971-1974 

Zu Rechnungsprüfern wurden ernannt: Herr J. M. Gaillard, Paris, und Herr A. 
Girod, Mailand. 

7. Mitgliedsbeitrag für die Periode 1971-1974 

Die jährlichen Beitragsraten von 10.00 S. Fr. für ordentliche Mitglieder und 5.00 
S. Fr. für korrespondierende Mitglieder wurden nicht geändert. 

8. Jahr und Ort des nächsten Kongresses 

Der gewählte Präsident, Dr. Toffoletto, hat die Mitglieder der UNITAS für den 
nächsten Kongress 1974 nach Mailand eingeladen. Diese Einladung wurde angenommen. 

9. Verschiedenes 

a)Liste der europäischen Malakologen und Bibliographie: Auf der letzten General- 
versammlung 1968 war Dr. Paget beauftragt worden, sich um die Weiterführung der 
Vorhaben zu bemühen, die unter den Punkten 2, 4, und 5 in dem "Resume" der "Presi- 
dential Address" (Proc. Third Europ. Malac. Congr., p 14) erwähnt sind. Inzwischen 
ist die "Liste der europäischen Malakologen 1971" erschienen. Sie kann bezogen werden 
von Dr. Oliver Paget, Naturhistorisches Museum, Burgring 7, A-1014 Wien, Österreich 
(5 Internationale Antwortscheine). Die Bibliographien für die Jahre 1969 und 1970 
(nur europäische Literatur) stehen ebenfalls zur Verfügung (kostenlos). Die Biblio- 
graphie für 1971 ist in Vorbereitung. Das unter Punkt 5 erwähnte Vorhaben wird 
fortgesetzt; Ergebnisse werden zur gegebenen Zeit veröffentlicht. 

b)Schutz der Mollusken: Der von der betreffenden Redaktionskommission vorge- 
schlagene Text eines Entschlusses wurde kiskutiert und nach einigen Veränderungen 
einstimmig angenommen (Siehe Seite 16). 



24 Stimmzettel sind zu spät abgeschickt worden und erreichten den Sekretär erst einige Tage 
nach der Generalversammlung. 



PROC. FOURTH EUROP. MALAC. CONGR. 

COMPTE-RENDU DE LA REUNION DE FAUNISTIQUE CONTINENTALE, 

le 10 septembre 1971 

Une réunion de travail sur les méthodes de collecte de données faunistiques dans le 
milieu continental avait été demandée par la Société Française de Malacologie. La 
participation, au Congrès de Genève, du Dr J. Heath, responsable anglais du "Euro- 
pean Invertebrate Survey" ("Cartographie des Invertébrés Européens"), a permis de 
donner à cette réunion une portée coordinatrice internationale. 

Les 28 malacologistes qui participèrent à cette réunion appartenaient aux pays 
suivants: Allemagne Fédérale, Australie, Finlande, France, Grande Bretagne, Hongrie, 
Norvège, Pays Bas, Suède et Suisse. Après l'exposé du Dr Heath sur les méthodes 
utilisées par Г "European Invertebrate Survey", plusieurs collègues prirent la parole 
pour décrire les méthodes employées, dans leur pays, par leurs Sociétés malacolo- 
giques ou par leurs Instituts de Recherche, pour annoncer les résultats obtenus, pour 
évoquer les problèmes non encore résolus et pour signaler les projets en cours. 

Les collègues présents à cette réunion ont, finalement, souhaité que les méthodes 
de cartographie préconisées par Г "European Invertebrate Survey" (représentation 
de la distribution d'une espèce à l'aide de signes ponctuels sur des cartes UTM 
muettes), soient adoptées par les malacologistes comme elles l'ont été par les ento- 
mologistes. Ils ont enfin exprimé le désir de voir se former une commission euro- 
péenne patronee par UNITAS MALACOLOGICA EUROPAEA. L'Assemblée générale 
de Г UNITAS, au cours de sa réunion du 11 septembre, a approuvé la création de cette 
commission et a confié les travaux de coordination à quatre responsables: MM. H. Ant 
(Allemagne Féd.), H. Chevallier (France), M. Kerney (G. B.) et H. Waldên (Suède). Ces 
quatre chercheurs se sont entendus pour prendre contact avec des collègues con- 
tinentalistes d'autres pays afin de constituer une Commission Faunistique Continentale 
Européenne, regroupant, si possible, un réprésentant de chaque pays européen. 

H. Chevallier 

Muséum National d'Histoire Naturelle 

55, rue Buffon, Paris 5e, France 



(13) 



PROC. FOURTH EUROP. MALAC. CONGR. 

WORKING CONFERENCE ON DISTRIBUTION MAPPING 
September 10th 1971 

This meeting was organised by the Commission Faunistique Continentale of the 
Société Française de Malacologie and was attended by 30 Congress members. The 
countries represented were France, Federal Germany, Switzerland, Netherlands, 
Sweden, Norway, Finland, Hungary, Australia and Great Britain. 

The methods being used by the European Invertebrate Survey for the production of 
maps of Europe were described by J. Heath. This project uses a 50 Km square 
derived from the UTM grid as the basic recording unit. Advanced data processing 
facilities are available at the Biological Records Centre, Monks Wood Experimental 
Station which, together with Professor Leclercq's Department of Zoology, Gembloux, 
Belgium, is acting as coordinating centre. 

M. H. Chevallier then explained the techniques being used by the Société Française 
de Malacologie for their survey. The use of the various recording sheets was explained 
in detail. 

Dr. M. Kerney of the British Conchological Society detailed the methods being used 
for their Atlas project which aims at producing complete species lists for each 10 Km 
square in Britain. A species list Field Card is used by the recorders for entering 
their data which, after checking, is transferred to a 'Master' card for each square. 
These are then processed and maps made by the Biological Records Centre. Some 
provisional maps have already been published. The data from this scheme will be 
made available to the European Invertebrate Survey. 

The German project was outlined by Dr. H. Ant who said that they had also en- 
countered the problems of identification mentioned by M. H. Chevallier. He said that 
they had now adopted the UTM grid as the basis for recording, although this had en- 
tailed converting much data from an earlier system. 

For the Netherlands Dr. Butot reported that originally mapping had not been carried 
out using the UTM grid, but that workers in his country had now changed over to that 
system. 

Dr. H. Waiden described the very detailed work which has been carried out in Sweden 
where mapping was at an advanced stage. Unfortunately very little had yet been done 
in Norway. A proposal to form a Scandinavian biological data bank was under dis- 
cussion. 

The meeting concluded by forwarding to the General Assembly of UNITAS MALACO- 
LOGICA EUROPAEA a resolution thatU.M.E. should sponsor and co-ordinate a scheme 
to map the molluscs of Europe in collaboration with the European Invertebrate Survey. 
This resolution was later unanimously adopted by the meeting on Saturday, September 
11th, 1971. The General Assembly appointed a committee comprising Dr. M. Kerney 
(U.K.), Dr. H. W. Waiden (Sweden), Dr. H. Ant (Germany (FR)) and M. H. Chevallier 
(France) to implement the resolution. 

J. Heath 

Biological Records Centre 
Monks Wood Experimental Station 
Abbots Ripton, Huntingdon, England 



(14) 



PROC. FOURTH EUROP. MA LAC. CONGR. 
MALACOLOGISTS AND THE PROTECTION OF MOLLUSCS 

Numerous species of molluscs are in the process of disappearing or are becoming 
rare. In 1968, the American Malacological Union held a symposium on the endangered 
species of North America, which came to the general conclusion that rarefaction is 
mostly due to the destruction or alteration of the environment. 

In South Africa, forest molluscs in the Capetown area disappear and are replaced 
by species accidentally imported from Europe. In tropical Africa, many species will 
unavoidably disappear if the felling of the rain forest goes on. This is especially 
serious from a scientific point of view, for many species are being destroyed even 
before they are known, which makes the study of phylogeny impossible. In this way, 
very interesting speciation cases escape analysis while they might have given precious 
information on the mechanism of this process. In some parts of Australia, the fauna 
is no longer to be found except in cemeteries where the sheep cannot penetrate and 
therefore have not been able to alter the environment. 

As regards marine molluscs, Mr. Torchio, in a conference given at the Congress of 
the Società Malacologica Italiana in 1970, has shown how rapidly pollution by fuel and by 
particles suspended in the water is eliminating the fauna, principally the molluscs, 
from the coasts of the Mediterranean Sea. In a session of June 1971, the American 
Western Society of Malacologists has dealt, among other subjects, with the pre- 
servation of the marine environment from the malacological point of view. 

The impoverishment of the fauna due to the degradation of the environment is a 
problem which concerns all biologists, and it is as biologists that we must strive 
with energy against this tendency whenever there is an opportunity. There would be 
no reason to put this problem on the agenda of a specifically malacological congress 
if it had not an aspect in which we are particularly concerned: Where the environment 
has not yet been destroyed and where molluscs are still abundant, they are endangered 
by overcollecting, especially with sales in view. This applies above all to marine 
molluscs. This activity has developed to a considerable extent in the course of the 
last fifteen years, owing to the multiplication of the number of amateurs, and still 
more to the extension of the means at disposal: organized travelling, fast speedboats, 
easy scuba diving within reach of nearly everybody. Many divers collect all that they 
see, without discrimination and without consideration. Others make a living out of it, 
plundering methodically and completely; then they move to another place and start 
afresh. Traders pay them and sell the shells to numerous collectors who are scarcely 
ever moved by scientific considerations, but are rather interested in the rarity of the 
species. 

Faced with this problem^ malacologists find themselves in an ambiguous position: 
Collectors have always existed and have furnished many museums with their first 
scientific collections. Scientists were among the first to profit by the use of scuba 
diving apparatus. Museums often have applied to shell dealers, many of whom are 
efficient and reliable in their information. Thus it is not easy for us to stand up 
unanimously against this activity of collecting molluscs. It is nevertheless evident 
that this process leads to deplorable excesses which reverberate on the ecological 
balance of the environment so that we run the risk of being deprived of good scientific 
material. For this reason, the president of U.M.E., Dr. E. Binder, took advantage of 
the IV. European Malacological Congress to raise this problem so that it may be ex- 
amined by all interested malacologists present. 

A meeting was held on the evening of September 8, attended by 56 congress members, 
to discuss the different aspects of the question and find a way in which to intervene. 

(15) 



16 PROC. FOURTH EUROP. MALAC. CONGR. 

The meeting came to the decision to ask the help of the councils of all malacological 
societies and of amateur shell-clubs in influencing the interest of their members 
and altering their perspective as to shell-collecting. A drafting committee was ap- 
pointed to prepare a resolution to be circulated among malacological societies and 
published in malacological journals as the official stand of UNITAS MALACOLOGICA 
EUROPAEA in this matter. As a result, the general Assembly on September 11 
adopted the following resolution: 

RESOLUTION ON THE PROTECTION OF MOLLUSCS 
adopted by the General Assembly of U.M.E., 11 September 1971 

UNITAS MALACOLOGICA EUROPAEA (U.M.E.), representing malacologists 
and conchologists in Europe, is much concerned by the rapidly increasing des- 
truction of the natural environment. It therefore supports all measures being 
taken to avoid and reduce this destruction. 

As Malacologists, we are particularly concerned with molluscs. Therefore, 
U.M.E. urges all who are concerned throughout the world to accept respon- 
sibility for ensuring the future existence of Mollusca and their habitats. 

We, the members of U.M.E., realize that this will necessitate a curtailment 
of collecting activities, but we are sure that, as responsible naturalists, all 
conchologists and malacologists will wish to support appropriate conservation 
measures. U.M.E. therefore urges that, for any purpose whatsoever, only 
about the minimum number of specimens shall be collected. Observation as 
well as photography of living specimens in their natural habitats may be a 
much more rewarding activity than mere collecting. This applies equally to 
the work of the amateur and the professional. Such an approach to field 
studies would result in the acquisition of much of the information which is so 
urgently needed to ensure the success of the efforts being made to conserve 
these animals. 



PAPERS and ABSTRACTS 



oí the 



FOURTH EUROPEAN MALACOLOGICAL CONGRESS 



(Geneva, 7-11 September 1971) 



MALACOLOGIA, 1973, 14: 19-27 

PROC. FOURTH EUROP. MALAC. CONGR. 

PALEOCENE MOLLUSKS FROM EWEKORO, SOUTHERN NIGERIA 1 

O. S. Adegoke 

Department of Geology, University oflfe 
lie -If e, Nigeria 

INTRODUCTION 

Marine macrofossil-bearing strata of Paleocene age show a patchy distribution all 
over the world. Among the best known circum-Atlantic/Tethyan sections may be 
mentioned the Danian beds at Faxe, Denmark (Ravn, 1933; Rosenkrantz, 1960), and at 
Copenhagen (Ravn, 1939; von Koenen, 1885); the Montian beds in Belgium (Briart and 
Cornet, 1871; Cossmann, 1908, 1913, 1924; Vincent, 1930); the Ranikot beds of India 
(Cossmann and Pissarro, 1909, 1927; Douvillé, 1928, 1929; Vredenburg, 1929; Cox, 
1930); the lower Mokattam beds of Egypt (Oppenheim, 1903, 1906); the Midway Group of 
the American Gulf Coastal Plain (Harris, 1896; Gardner, 1933); the Kangilia and Agat- 
dal formations of West Greenland (Rosenkrantz, 1970), the Maria Farinha beds of 
Pernambuco, Brazil (White, 1887; Penna, 1965), and the Soldado Formation of Trinidad 
(Rutsch, 1943). 

Fossiliferous marine Paleocene has also been reported from scattered West African 
localities, the best known being the Landana beds of Congo (Vincent, 1913; Miller, 
1951); various localities in Senegal (Tessier, 1952), Morocco (Salvan, 1954), Soudan 
(Douvillé, 1920); the Adabion and Togblekové beds in Togo (Oppenheim, 1915; Furon, 
1948) and the Apatuema beds of Ghana (Cox, 1952). 

In Nigeria, marine macrofossil-bearing Paleocene is represented in the southwest 
by the Ewekoro Formation, a shelly limestone exposed in the quarry of the West 
African Portland Cement Company Limited at Ewekoro (Fig. 1). 

Until the initiation of the present series of studies by the writer in 1967, little was 
known about the macrofauna of the Ewekoro Formation. Rey ment (1966a) described a 
fragmentary Cimomia from the quarry which he erroneously assigned to Cimomia 
landanensis (Vincent). He mentioned also the occurrence of Deltoidonautilus togoensis 
(Oppenheim). More recently, Adegoke and Dessauvagie (1970) described a new Cam- 
panile, C. nigeriense from the Quarry. 

A recently completed study (Adegoke, in preparation) has led to the recognition of 
over 220 species of macrofossils in the quarry material. This well preserved fauna 
(see Plates 1 and 2) is dominated by microform mollusks. The Ewekoro quarry thus 
becomes one of the most fossiliferous Paleocene sections recorded to date. The 
present paper reviews the salient aspects of the fauna. 

STRATIGRAPHY 

The Ewekoro Formation at the type locality consists of about 12.5 metres of shelly 
limestone. It is sandy near the base and grades into the underlying Abeokuta Forma- 



1 This paper is based on research carried out while the writer held a Visiting Research Asso- 
ciateship at the Smithsonian Institution, Washington, D. C. The opportunity to use the Museum 
and other facilities is gratefully acknowledged. Thanks also are due to the University of If e, 
Nigeria for financial support. The completed monograph, including the description of new taxa 
will be published in the Smithsonian Contributions to Paleobiology. 

(19) 



20 



PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 1. Map of western Nigeria showing location of Ewekoro. 

tion (Fig. 2). The formation was formally named by Jones (1964) who included within 
it the overlying shale which has subsequently been referred by Ogbe (1971) to the 
Akinbo Formation. Details of the stratigraphy and petrography of the Formation were 
published by Adegoke and others (1971) who erected three microfacies units, the 
Sandy Biomicrosparite at the base, overlain by the Shelly Biomicrite and the Algal 
Biosparite. More recently, Ogbe (1972) proposed a fourth unit, the Red Phosphatic 
Biomicrite, represented by thin erosional remnants, less than 1 metre in thickness 
overlying the Algal Biosparite. Most of the fossils studied were preserved in the 
Shelly Biomicrite. 

FAUNA 



The Ewekoro macrofauna contains over 200 determinable species, most of which are 
new. The fauna is dominated by mollusks (gastropods ca. 125 species, pelecypods 
ca. 70 species, nautiloids 6 species, scaphopods 3 species). Corals are represented by 
7 species many of which are new. Of 5 echinoid species collected, only 3 referred to 
the genera Togocyamus, Cassidulits and Thylechinus are determinable. A probable 
crinoid stem fragment was also collected. Arthropods were abundantly represented 
by fragmentary ambulatory appendages of the cosmopolitan Tertiary genus, Callia- 



ADEGOKE 



21 




gtauconite localities 3 &¿ 



glauconite localities 1&2 



Red Phosphatic Biomicrite 
Algal Biosparite 



Shelty Biomicrite 



Sandy Biomicrosparite 



FIG. 2. Stratigraphie Section of Strata exposed in the Ewekoro quarry, 
radiometrically dated glauconite samples. 



Note location of the 



nassa. Vertebrates were sparsely represented by teeth and denticles of Myliobatis, 
Odontaspis and other unidentified sharks and rays. 

The molluscan assemblage is dominated by gastropods not only in species diversity 
but also in total number of individuals. The gastropod-pelecypod ratio is about 2 to 1, 
whereas their numerical ratio is over 10 to 1. 

The greatest gastropod diversity is seen among the submicroscopic size (1-3 mm) 
forms. Genera such as Pseudomalaxis, Heligmotoma, Pseudoliva, Rimella, Cerithi- 
opsis, Sycostoma, Mesalia and Haustator showed remarkable species diversity though 



22 



PROC. FOURTH EUROP. MALAC. CONGR. 
PLATE 1 




ADEGOKE 
PLATE 2 



23 




EXPLANATION OF PLATES 



(Abbreviations: UIMG = University of Ife Museum of Geology; 
USNM = United States National Museum) 



1. 
2. 

3. 



FIG. 
FIG. 
FIG. 

FIG. 4. 

FIG. 5. 

FIG. 6. 

FIG. 7. 

FIG. 8. 

FIG. 9. 

FIG. 10. 

FIG. 11. 

FIG. 12. 

FIG. 13. 

FIG. 14. 

FIG. 15. 



Clinuropsis diderrichi Vincent, UIMG no. 153, XI. 

Gisortia brevis Douvillé, UIMG no. 152, XI. 

? Clavocerithium n. sp. , USNM no. 174744, X2. 

Torquesia adabionensis Oppenheim, USNM no. 174741, XI /2 . 

Tomatellaea (Ravniella) africana Furon, USNM no. 174745, X7. 

Campanile nigeriense Adegoke and Dessauvagie, UIMG no. 20, XL 

Velates n. sp. , USNM no. 174740, XL 

Pseudoliva (Buccinorbis) n. sp. , UIMG no. 159, XlV 2 . 

Heligmotoma n. sp. , USNM no. 174747, XL 

Fimbria subdavidsoni Furon, USNM no. 174755, XlV 2 . 

Venericardia (Venericor) n. sp. , UIMG no. 158, XI / 2 - 

Cimomia n. sp. , UIMG no. 128, XL 

Pseudoliva (Buccinorbis) n. sp. , USNM no. 174753, XlV 2 . 

Cypraea n. sp. , UIMG no. 155, XlV 2 . 

Eocypraea n. sp. , UIMG no. 150, XL 



24 PROC. FOURTH EUROP. MALAC. CONGR. 

rarely accompanied by a commensurate numerical abundance. Among the most abun- 
dant species may be mentioned Pseudaulicina simplex Furon, Strepsidura kerstingi 
Oppenheim, Clinuropsis togoensis (Oppenheim), Volutilithes uniplicata Furon, Solari- 
ella n. sp., Clavilithes (Cosmolithes) n. sp. and Pseudoliva n. sp. 

Bivalves are in general less diverse and less numerous than gastropods. The 
genera Ostrea, Venericardia, Macrocallista, Corbula, Glycymeris and Cardium showed 
a diversity both in number of species and (except for Glycymeris) in number of indi- 
viduals. Cardium zechi Oppenheim and Corbula n. sp. were numerically the most 
abundant. 

The nautiloid fauna is diverse and represents one of the most diverse and most 
abundant known for strata of comparable age. This renders unnecessary Rey ment' s 
(1966a) suggestion that empty nautiloid conchs were supplied to the coasts of Nigeria 
and Togo via a hypothetical north-drifting paleo-oceanographic current from the 
Cabinda enclave in Angola. Besides, the most abundant Ewekoro species are forms 
with very large body chambers more than one and a half whorls long. According to the 
results of Reyment's (1958) biostratonomic experiments, such forms would rarely 
stay afloat for the 3,500-4, 000 kilometres between the Cabinda enclave and the Nigeria- 
Togo shoreline. 

TETHYAN AFFINITIES 

The great similarity between West African Paleogene faunas and those of distant 
Tethyan provinces of India, Egypt and the Gulf Coastal United States has attracted the 
attention of many earlier workers (see Newton, 1922; Cox, 1930; Davies, 1934). This 
coupled with the gross dissimilarities between these faunas and those of neighbouring 
North African and European areas led Douvillê (1920), for example, to refer to them as 
an Indo-African fauna. 

The Tethyan affinity of the Ewekoro fauna was stressed by the writer (Adegoke, 1972a, 
1972b). This is confirmed by the presence in it of the following genera commonly 
associated with the Tethyan seaway (see Palmer, 1967): Nummulite s , Gisortia, Velates, 
ITerebellum, Carolia, Campanile, Crommium, Venericardia, Fimbria, etc. (see Plates 
1 and 2). In addition, a few specimens of a new genus previously referred to ?Clavo- 
cerithium (see Palmer and Brann, 1966) were also collected. 

Until recently, Nummulites was considered absent from West Africa south of Senegal 
and the area was, in fact, mapped as part of the "non-nummulitic faciès" by Davies 
(1934). The record of a new species of Nummulites (Sachs and Adegoke, in press) 
from Ewekoro is significant not only because it further extends the range of the 
genus in West Africa (see Blondeau, 1966) but also confirms the suggested connection 
of the West African Paleogene basins with the Tethyan sea via a trans-saharan 
epeiric seaway (see Reyre, 1966; Adegoke, 1969). 

Further evidences of close Tethyan affinity are furnished by the parallel develop- 
ment of species of Strepsidura, Torquesia, Mesalia, Collonia, Heligmotoma, Solariella, 
Cardita, etc., between Ewekoro and the contemporaneous Tethyan faunas of the Ranikot 
beds of India and the Mokattam beds of Egypt. Comparable species of Calyptraphorus, 
Surcula, Volutilithes, Buccinorbis, Mesalia, Cimomia, Venericardia and Cucullaea 
also occur in Ewekoro and the Midway Group of the United States Gulf Coastal Plain. 

AGE OF THE EWEKORO FORMATION 

Apart from Fayose and Asseez (1971), all workers to date assign the Ewekoro 
Formation to the Paleocene. The former assigned an Eocene age to the formation on 
the basis of a single record of Pseudohastigerina in a limestone facies penetrated by 



ADEGOKE 25 

a borehole located a few kilometres from the Ewekoro quarry. Their claim has sub- 
sequently been disregarded because the log of the borehole showed that no sample was 
collected from the interval from which Pseudohastigerina was presumably recorded. 

Reyment (1966b) and Ogbe (1972) recorded the following planktonic formaminifera 
from the Ewekoro Quarry: Globorotalia acuta Toulmin, G. velascoensis (Cushman), 
G. varianta (Subbotina), G. pseudobulloides (Plummer) and Globigerina triloculinoides 
(Plummer). These suggest a Paleocene age. 

Ostracods from the formation were recently re-examined by Dr. M. E. Omatsola 
of the Paleontological Institute, Uppsala who identified 31 species. He considered the 
assemblage diagnostic of the upper Paleocene (Omatsola, 1970, personal communica- 
tion). 

Apart from the affinities of the Ewekoro macrofauna with faunas of well known 
Paleocene horizons discussed earlier, a few diagnostic Paleocene species occur at 
Ewekoro. Clinuropsis diderrichi Vincent, first recorded in the Paleocene of Landana, 
Congo (Vincent, 1913) has been found in contemporaneous strata in Togo, Ghana and 
Senegal (see Cox, 1952; ^essier, 1952). It was also recorded in the Soldado rock in 
Trinidad (Rutsch, 1943). 7 ¿rnatellaea (Ravniella) africana Furon, a common Ewekoro 
form belongs to a subgenus which according to Rosenkrantz (1970) is so far known to 
be restricted to the lower Paleocene. The pelecypod Fimbria subdavidsoni Furon, 
also common at Ewekoro is virtually indistinguishable from F. davidsoni (Deshayes) 
from the Thanetian of the Paris Basin (see Farchad, 1936). It should also be mentioned 
that the Paleocene index echinoid, Togocyamus seefriedi Oppenheim occurs abundantly 
in the Ewekoro Formation. 

Finally, radiometric (K-Ar) age determination of glauconites in the Akinbo shale 
which dis conformably overlies the Ewekoro Formation (see Fig. 2) yielded a date of 
54.45 ±2.7 million years (Adegoke and others, 1972). This age closely corresponds 
to the Paleocene-Eocene transition of Berggren (1969) and conclusively proves that 
the underlying Ewekoro Formation cannot be younger than late Paleocene. 

SUMMARY 

A fauna containing over 200 determinable species has been recorded from the Paleo- 
cene Ewekoro Formation of southwestern Nigeria. The fauna shows strong genetic 
affinities with contemporaneous Tethyan faunas of India (Ranikot beds), Egypt (Mokattam 
beds), United States Gulf Coastal Plain (Midway Group), Trinidad (Soldado Rock) and 
West Africa (Togo, Ghana, Senegal and Landana). 

The Tethyan affinity is confirmed by the presence of Nummulites, Gisortia, У elates, 
ITerebellum, Carolia, Campanile, Crommium, Venericardia and Fimbria. 

The Paleocene age is confirmed on the bases of planktonic foraminiferal, ostracode 
and macrofossil evidences as well as a radiometric age of 54.45 ±2.7 million years 
obtained for glauconitic beds which overlie the Ewekoro formation dis conformably. 

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26 PROC. FOURTH EUROP. MALAC. CONGR. 

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REYRE, D., 1966, Particularités géologiques des Bassins cotiers de l'ouest Africain 

(essai de recapitulation). In: Sedimentary Basins of the African Coasts. 1st 

Part. Atlantic Coast. New Delhi, 1964: 253-304, 14 figs. 
ROSENKRANTZ, A., 1960, Danian Mollusca from Denmark. Rept. intern, geol. Congr., 

XXI Sess., Norden, 5: 193-198. 
ROSENKRANTZ, A., 1970, Marine Upper Cretaceous and lowermost Tertiary deposits 

in West Greenland. Meddr. dansk. Geol. Foren., 19(4): 406-453, figs. 1-16. 
RUTSCH, R., 1943, Die Paleocaen-Mollusken der Inseln Trinidad und Soldado Rock 

(British Westindien). Eclog. geol. Helv., 36(2): 139-192, pis. 3-5. 
SACHS, K. N. & ADEGOKE, O. S., 1972, Paleocene Nummulites from Nigeria. Proc. 

5th Afr. Micropal. Coll., Addis Ababa, 1972 (In press, Rev. Esp. de Micropal.) 
SALVAN, H., 1954, Les Invertébrés Fossiles des phosphates Marocains. Tome II. 

Paléontologie. Notes et Mémoires, Div. Min. Geol., 93: 1-257, pis. 1-18. 
TESSIER, F., 1952, Etudes stratigraphique sur l'Ouest Senegal. I. Contribution à la 

Stratigraphie et à la Paléontologie de la partie Ouest du Sénégal (Crétacé et 

Tertiaire). Bull. Div. Mines., 14(1, 2): 1-465, pis. 1-40. 
VINCENT, E., 1913, La Faune paleocene de Landana. Mollusques. Ann. Mus. roy. 

Congo belge, Geol. Paléont. Miner., ser„ IH. - Bas-et Moyen Congo. 1(1): 1-46, 

pis. 1-6. 
VINCENT, E., 1930, Etudes sur les Mollusques Montiens du Poudingue et du Tuffeau 

de Ciply. Mem. Mus. roy. Hist, natur. Belg., 46: 1-115, pis» 1-6. 
von KOENEN, A., 1885, Über eine Paleocäne Fauna von Kopenhagen. Abh. K. Ges. 

Wiss. Göttingen, 32: 1-128, pis. 1-5 
VREDENBURG, E. W., 1929, A supplement to the MoUusca of the Ranikot Series. 

Palaeontologia Indica, n.s., 10(4): 1-75, pis. 1-9. 
WHITE, C. A., 1887, Contributions to the Paleontology of Brazil. Archos Mus. пас. 

Rio de J«, 7: 1-273, pis. 1-28. 



MALACOLOGIA, 1973, 14: 29-32 

PROC. FOURTH EUROP. MA LAC. CONGR. 

FAUNENGESCHICHTLICHE BEDEUTUNG DER ALTPLEISTOZÄNEN 
MOLLUSKENFAUNA VON UNGARN 

E. Krolopp 

Ungarische Geologische Anstalt 
Budapest, Ungarn 

Die Wurzeln unserer Molluskenfauna reichen bis auf das Ende Tertiär zurück. 
Obwohl uns aus dem Pliozän des Karpaten-Beckens 41, auch heute noch lebende, Arten 
bekannt sind, weicht die spättertiäre Gastropodenfauna von der heutigen trotzdem 
wesentlich durch die ausgestorbenen beziehungsweise "exotischen" Arten, sogar 
Gattungen ab (Krolopp, 1969). 

Es ist daher verständlich, dass für die Faunenentwicklung die f rühr en Stufen des 
Quartärs (unteres Pleistozän) von entscheidender Bedeutung sind. 

Aus dem unteren Pleistozän von Mittel- und Westeuropa sind schon lange solche 
ausgestorbenen oder dort heute nicht lebenden Arten bekannt, die Beziehungen zu dem 
Süden und Südosten aufweisen oder auch heute noch im Süden leben. Das Karapaten- 
Becken, das in Richtung Süden und Südosten offen war, stellte ein Gebiet von Schlüssel- 
bedeutung für die altpleistozäne Verbreitung dieser Arten, für die Fixierung ihrer 
Bewegungen in der Zeit dar. 

Da ich in jüngster Zeit Gelegenheit hatte, die Molluskenfauna von zahlreichen alt- 
pleistozänen Lokalitäten zu bearbeiten, deren Alter mit vertebratenpaläontologischen 
Angaben genau bestimmt werden konnte, erhielt ich auch faunengeschichtlich wertvolle 
Daten. 

Aus den altpleistozänen terrestrischen Steh- und Flusswasserablagerungen konnte 
ich eine Gesamtzahl von 102 Arten bestimmen. 

Die meisten terrestrischen Arten sind bereits heute lebende Formen von grossem 
Verbreitungsareal. Neben diesen bedürfen einer besonderen Erwähnung zwei Gastro- 
copta- Arten, von denen eine die aus dem älteren Teil des unteren Pleistozäns der 
Tschechoslowakei und Osterreich bekannte Gastrocopta serótina Loz. (Lozek, 1964) 
ist, die andere eine neue, noch nicht beschriebene Art aus dem jüngeren Altpleistozän 
darstellt. Die beiden Gastrocopta -Arten können als altpleistozäne Relikte der im 
Pliozän von Mitteleuropa ziemlich weit verbreiteten Gattung betrachtet werden, die 
jedoch sich gut von den pliozänen Arten unterscheiden lassen. 

Die von Lozek beschriebene Art Zonitoides sepultus Loz. war ausser einigen 
tschechoslowakischen Lokalitäten nur aus Schmiechen (Deutschland) bekannt (Lozek, 
1964). Jetzt wurde sie auch im jüngeren Altpleistozän von Ungarn angetroffen. 

Schlieslich möchte ich bemerken, dass aus dem unteren Altpleistozän eine Parma- 
cella-Art bekannt geworden ist. Die Gattung lebt - wie bekannt - in Südeuropa und im 
Räume des Kaukasus (Zilch, 1959-60). 

Das sind also im Vergleich mit den heutigen fremde Elemente der altpleistozänen 
terrestrischen Gastropodenfauna von Ungarn. 

Die Basommatophoren der ungarischen altpleistozänen Ablagerungen sind im Allge- 
meinen auch heute noch lebende, weit verbreitete Arten. Von den Besonderheiten ist 
eine Gundlachia-Art am interessantesten. Es ist bekannt, dass in den letzten Jahren 
aus Mittel- und Südwesteuropa zahlreiche solche Angaben über Ancyliden bekannt 
wurden, die mit den Vertretern der subtropisch-tropischen Gattung Gundlachia 
beziehungsweise Ferrissia verglichen wurden (Zilch-Jaeckel, 1962, Mirolli, 1960, 
Wautier-Odiévre, 1961, Pintér, 1968). Ein Teil der Vorkommen könnte zwar auf 

(29) 



30 PROC. FOURTH EUROP. MALAC. CONGR. 

Einschleppen zurückgeführt werden, aber nach meiner soeben erwähnten Angabe, 
hat die Gattung Gundlachia im unteren Pleistozän im Karpaten-Becken noch gelebt. 
Sie war also Mitglied der Fauna von Mitteleuropa. Da zur dieser Zeit auf unserem 
Gebiet auch noch die gegenwärtig in Südeuropa verbreitete Parmacella lebte, kann 
man die südwesteuropäischen Angaben über die Gundlachien als Vorkommen einer 
Gattung zu deuten, die sich in den jüngeren Stufen des Pleistozäns nach Süden zurück- 
gezogen hat und dort noch immer lebt. 

Eine andere Merkwürdigkeit unserer altpleistozänen Basommatophoren-Fauna ist 
eine Acella-Art. Die zoogeographischen Beziehungen dieser, mit Lymnaea verwandten, 
Gattung sind vorderhand nicht geklärt, da zur Zeit uns lediglich aus Nordamerika 
einige lebende Vertreter der Gattung bekannt sind (Zilch, 1959-60). Da aber in den 
pliozänen Ablagerungen des Karapaten-Beckens auch mehrere Vertreter der Gattung 
angetroffen wurden, ist es wahrscheinlich, dass die altpleistozäne Art mit einem von 
diesen generisch zu verbinden sei. 

Die Prosobranchiaten-Arten der altpleistozänen Fauna sind zumeist aus jenen 
fluviatilen Ablagerungen zum Vorschein gekommen, die in einer Wechsellagerung mit 
Stehwasser -Sedimenten unter der Oberfläche der Grossen Ungarischen Tiefebene 
eine über 800 m mächtige pleistozäne Schichtenfolge bilden. Im Laufe der malakolo- 
gischen Untersuchungen der Bohrkerne hat es sich herasgestellt, dass der grösste 
Teil der Schichtenfolge vom Altpleistozän stammt und die mächtigkeit der jung- 
pleistozänen Schichten ein Maximum von 100 m erreicht. Die Gliederung der Sediment- 
folge in diese zwei Komplexe wurde gerade durch die Untersuchungen der Mollusken- 
fauna ermöglicht (Krolopp, 1970). Unter den altpleistozänen fluviatilen Schnecken gibt 
es nämlich - neben den heute lebenden Arten - einige Formen, die im Quartär ausge- 
storben sind und schon in den jungpleistozänen Ablagerungen nicht angetroffen werden 
können. 

Von diesen möchte ich zunächst Viviparus böckhi (Halav.) erwähnen, die wahr- 
scheinlich eine endemische altpleistozäne Art des Karapaten-Bekens ist, aber eine 
nahe Verwandtschaft zu den aus Dnjester-Terrasen beschriebenen Viviparus-Formen 
aufweist (Tschepalyga, 1971). Eine andere Merkwürdigkeit ist eine noch nicht be- 
schriebene Bithynia-Art, die grösser als Bithynia tentaculata (L.) ist und ein charak- 
teristisches excentrisches Operculum besitzt. Eine Ebenfalls neue Art ist eine Hydro- 
bia, die Verwandtschaft mit den pliozänen Prososthenien aufweist. 

Zur Gruppe der ausgestorbenen Arten gehört auch noch eine Muschel, Pisidium 
clessini Neum., die auch aus den mittelpleistozänen Ablagerungen bekannt ist. 

Eine andere Gruppe der altpleistozänen fluviatilen Formen bilden solche Arten, die 
aus den alt- und mittelpleistozänen Interglazialen vom westlichen Mitteleuropa 
beziehungsweise von Westeuropa bekannt sind, aber in den jüngeren pleistozänen und 
rezenten Faunen dieser Gebiete fehlen (Steusloff, 1953), während sie in den im 
Karapaten-Becken befindlichen Flüssen des Wassersystems der Donau und in Südost- 
Europa auch heute noch leben (z.b. : Fagotia acicularis (Fer.), Fagotia esperi (Fer.), 
Theodoxus danubialis (C.Pfr.)). Auf Grund der erwähnten Angaben hat es sich erwiesen, 
dass diese Arten - offenbar wegen klimatischer Effekte - auch im Karapaten-Becken 
in den fluviatilen Ablagerungen seit dem Mindel-Glazial fehlen, aber im Holozän 
wieder erschienen. 

Etwa einen Übergang zwischen den beiden Gruppen bildet die Muschel Corbicula 
fluminalis (MUH.), die zwar in Vorder- und Mittelasien auch heute noch lebt, in Europa 
aber ausgestorben ist, während sie in den altpleistozänen und älteren mittelpleisto- 
zänen Schiefen von Mittel- und Westeuropa an zahlreichen Stellen angetroffen wurde 
(Zilch-Jaeckel, 1961). Aus ungarischen Tiefbohrungen wurde sie ebenfalls an mehreren 
Stellen bekannt. 

Die Arten der altpleistozänen fluviatilen Fauna von Ungarn stimmen also mit 



KROLOPP 31 

jenen überein, die uns auch schon früher als characteristische altpleistozäne Mollusken 
von Mittel- und Nordwest-Europa bekannt waren. Andere Arten lassen sich jedoch in 
eine Verwandschaft mit den westlichen Formen bringen. So dürfte unsere Art Vivi- 
parus böckhi (Halav.) vielleicht mit V. diluvianas (Kunth), beziehungsweise V. d. 
glacialis (S. V. Wood) verwandt sein. Die in unserem Altpleistozän häufige Art der 
Gattung Theodoxus vereinigt die Merkmale von Th. danubialis (C.Pfr.) und Th. 
prévostianus (C.Pfr.) in sich. Die aus dem unteren Pleistozän des Rheinlandes be- 
kannte Th. serratiliniformis (Geyer) kann man vielleicht als ihren westlichen Vertreter 
nehmen, während Th. prévostianus (C.Pfr.) selbst ihre in Thermalquellen und in 
Quellen von ständiger Temperatur erhalten gebliebener und an die dortigen Verhält- 
nisse angepasste Form zu sein scheint. Hier sei noch erwähnt, dass in unserem alt- 
pleistozänen Material die Merkmale der Arten Fagotia acicularis (Fér.) und F. esperi 
(Fer.) noch vermischt vorkommen, was auf ihre geneinsame Herkunft hinweist, worauf 
an Hand eines ungarischen Pliozän-Materials früher auch schon Bartha hingewiesen 
hat, der die Art Melanopsis fuchsi Handm. für den gemeinsamen Vorfahren dieser 
beiden Arten hielt (Bartha, 1956). 

Die altpleistozäne Molluskenfauna von Mitteleuropa benötigt weitere Untersuchungen, 
damit die Verwandtschaftsbeziehungen geklärt werden können. Allerdings kann das 
gegenwärtig laufende Studium des in den letzten Jahren gefundenen reichen ungarischen 
Mareriales neue wertvolle Angaben zu diesen Untersuchungen liefern. 

LITERATUR 

BARTHA, F., 1956, A tabi pannóniai korú fauna. Die pannonische Fauna von Tab. 

M. Állami. Földt. ínter. Évk., 45(3): 481-543 (magy.)., 545-579 (deutsch). 
KROLOPP, E., 1969, Faunengeschichtliche Untersuchungen im Karpatenbecken. 

Malacologia, 9(1): 111-119. 
KROLOPP, E., 1970, Öslenytani adatok a nagyalföldi pleisztocén és felsöpliocen 

rétegek sztratigráfiájához. -Paläontologische Beiträge zur Stratigraphie der pleis- 

tozänen- oberpliozänen Schichtenfolge der Grossen Ungarischen Tiefebene. 
v Öslenytani Viták, 14: 5-39 (magy.), 41-43 (deutsch). 
LOZEK, V., 1964, Neue Mollusken aus dem Altpleistozän Miteleuropas. Arch. 

Molluskenk., 93(5-6): 193-199. 
MIROLLI, M., 1960, Morfologia, biologia e posizione sistemática di Watsonula wautieri, 

n.g., n.s. (Basommatophora, Ancylidae). Mem. Inst. Ital. Idrobiol., 12: 121-163. 
PINTER, L, 1968, A magyarországi sapkacsigák (Ancylidae) újabb alakjai. Neue 

Formen der Ancylidae-Schnecken in Ungarn. Állatt. Közl., 55(1-4): 97-103 

(magy.), 104 (deutsch). 
STEUSLOFF, U., 1953, Wanderungen und Wandlungen der Süsswasser-Mollusken 

Mitteleuropas während des Pleistozäns. Arch. Hydrobiol., 48(2): 210-236. 
TSCHEPALYGA, A. L., 1971, Molljuski. Mollusca. In: Nikiforova, K. V., et al.: 

Pleistocene of Tiraspol, p 41-54 (russ.). 
WAUTIER, J., ODIEVRE, M., 1961, Le genere Gundlachia Pfeiffer (Mollusque, 

Ancylidae) en France. Verh. int. Verein, theor. angew. Limnol., 15: 983-987. 
ZILCH, A., 1959-60, Euthyneura. Handb. d. Paläezool., 6, Teil 2 (1-3), Berlin. 
ZILCH, A. & JAECKEL, S. G. A., 1962, Ergänzung zu P. Ehrmann: Mollusken (1953), 

294 p. Leipzig. 

SUMMARY 

With its extinct or "exotic" species and even genera, the Latest Tertiary mollusc 
fauna of Central Europe differs considerably from the now-living forms. The Middle 



32 PROC. FOURTH EUROP. MALAC. CONGR. 

Pleistocene fauna, however, is essentially identical with the contemporary one. Ac- 
cordingly, the Lower Pleistocene was crucial for faunal evolution. 

Open to the S and SE, the Carpathian Basin in Central Europe was a key area on the 
path of northward proliferation of southerly forms during the interglacials. Therefore 
the analysis of the 102 mollusc species identified in recent years in the Lower Pleisto- 
cene sediments of Hungary supplies data that are important for both the understanding 
of the fauna of the older member of the Pleistocene and the faunal history of Central 
Europe as a whole. In this connection it is worth mentioning that the present writer 
could show the presence of the genera Parmacella and Gundlachia in the Lower 
Pleistocene of Hungary (and, consequently, of Central Europe). The last-mentioned 
data imply, at the same time, a new approach to the explanation of the occurrences of 
Gundlachia and Ferrissia in Europe. Surprisingly enough, among the Lower Pleisto- 
cene forms the features of some species, readily distinguishable at present, are still 
mixed, indicating their origin from a common ancestor (e.g., Fagotia acicularis (Fer.) 
and Fagotia esperi (Fer.) or Theodoxus danubialis (C.Pfr.) and Th. prêvostianus 
(C.Pfr.), respectively). 



MA LA С O LOGIA, 1973, 14: 33-37 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE EARLIEST OCCURRENCE OF MACOMA BALTHICA (L.) AS A FOSSIL 
IN THE NORTH SEA DEPOSITS 

P. E. P. Norton and G. Spaink 

Zoology Dept., Glasgow University, Scotland and 
Netherlands Geological Survey, Haarlem, Netherlands 

ABSTRACT 

Macoma balthica is found first in the late Baventian of Mundesley, Sidestrand, 
West Runton and Sheringham, in Norfolk. It occurs by derivation in Pastonian 
sites close to these, but not elsewhere in the East Anglian 'Crag' succession. 
An hypothesis is offered, explaining this on tectonic grounds. Records of M . 
balthica from the Calabrian of Italy and the 'Icenien' of Holland are considered 
incorrect. A brief discussion of the paleogeography and immigration times of 
M. obliqua, M. praetenuis and M. calcárea is also given. 

PALEOGEOGRAPHY 

The Macoma species, M. obliqua, M. praetenuis, M. calcárea and M. balthica, 
appeared newly in the North Sea Basin deposits in the Pliocene and early Pleistocene 
time. Their points of origin and route of immigration are unknown to us. Discussion 
may begin with paleogeographic concepts of the later Tertiary time. There are dif- 
fering claims for what the paleogeography was. Strauch (1971) considers that Atlantic 
and Scandic marine provinces existed. A land barrier, the Thule Province, separated 
them. It ran from Greenland to Europe and included Iceland, the Faroes and Britain» 
The Atlantic province included that part of the Atlantic Ocean which is bounded by 
the continental shelf of Ireland, Iceland, the southern tip of Greenland and eastern 
North America. Deep gulfs extended into the present Mediterranean Sea and Davis 
Strait. The Scandic province included what is now the Greenland and Barents seas, 
connecting northward with the North Eurasian Basin and extending southward into the 
North Sea as a narrow gulf. Other workers claim that the later Tertiary paleogeo- 
graphy was substantially similar to the present. The North Sea and proto English 
Channel were connected across the present Pas de Calais. There was an open connec- 
tion from the North Sea to the Atlantic as at present. Spaink' s findings (unpublished) 
on the evolution of the Astartidae would support the latter paleogeographic reconstruc- 
tion. The Macoma evidence inclines us to keep both theories in mind. Macoma species 
were, at any rate, evolving in the North Sea and Arctic seas at this time. 

MACOMA OBLIQUA (Sowerby) 

In the Coralline Crag of England, which was forming during the Pliocene, is found 
Macoma obliqua. The diagnostics of this species as compared with the other species 
of Macoma mentioned here have been given and figured by Spaink & Norton (1967) and 
are not repeated here. M. obliqua is extinct today. Its Pliocene range also included 
the Scaldisien of the Netherlands and Belgium. 

By the beginning of the Pleistocene it appears that, even if the Scandic and Atlantic 
provinces had been separate previously, they were now united and so were the Pacific 
and Arctic Oceans. The Bering Strait had been submerged during the Beringian trans- 

(33) 



34 PROC. FOURTH EUROP. MALAC. CONGR. 

gression (Hopkins 1967). Foraminiferal studies of the East Anglian Crag deposits 
(Funnell 1961) indicate that the Pas de Calais Strait became closed during the early 
Pleistocene. It is inferred by van Voorthuysen (1954) that tectonic movements caused 
rising of the land in the southern North Sea at this time. The Pas de Calais Strait 
was open during the time of deposition of the Waltonian and Newbournian Red Crag and 
the early Ludham Crag. When the Butleyan Red Crag and the Norwich Crag Series 
above the early Ludham Crag were being deposited, the Strait was closed. (It is not 
yet known whether the Ludham Crag may be correlated with any part of the Red Crag 
Series). 

MACOMA PRAETENUIS (Leathes) and M. CALCÁREA (Gmelin) 

In the topmost Pliocene of the Netherlands and Belgium and in the earliest Pleisto- 
cene (Waltonian) of England occurs Macoma praetenuis . Macoma calcárea appears 
shortly afterward, in the Netherlands' 'Icenien' and the English Newbournian. M. 
praetenuis occurs also in the Icelandic succession at Tjörnes, beginning just below the 
currently recognised Pliocene-Pleistocene boundary (in Horizon 13/l of Strauch (1963); 
M. calcárea was present earlier). 

Macoma species also reached the Mediterranean, where in the marine Calabrian 
deposits Moroni (1967) found a shell named by her as M. balthica though on the basis 
of her figure we judge it to be a form of M. obliqua. 

In the early Pleistocene North Sea Deposits there is evidence for cycles of climatic 
change, indicated by procession from temperate to subarctic vegetation (West 1968) 
and Foraminifera (Funnell 1961). After the Pas de Calais Strait finally became land, 
the North Sea appears to have become rather shallow and brackish in the East Anglia 
region. The Southeastern part (the present Netherlands and Belgium) rather soon be- 
came nonmarine. Zagwijn (1963) found that in the Western Netherlands the 'Icenien' 
sea receded and continental conditions began during a late cool phase (Pollen Subzone 
TC4c) of the Tiglian Interglacial. Zagwijn (personal communication) suggests this 
may be correlated with the (East Anglia) Thurnian. The East Anglian basin remained 
marine much longer (Spaink & Norton 1967). 

MACOMA BALTHICA (Linnaeus) 

A new Macoma species, M. balthica, is first recorded from marine deposits of the 
late Baventian on the north coast of Norfolk. Pollen spectra in clays of this Stage 
indicate open heath oceanic vegetation (West 1961) and similar pollen occurs in clays 
associated with the Macoma balthica deposits. M. balthica is not found in Baventian 
deposits elsewhere in East Anglia. Preliminary findings (Beck, personal communi- 
cation) of the U.E. A. Research Boreholes programme allow us to speculate that the 
north and south parts of the deposition basin were separated by a chalk ridge running 
northeast towards Halesworth (Fig. 1). The Northern Basin subsided during Ludhamian 
times. Both parts, except for North Norfolk, subsided during Thurnian, Antian and 
Baventian times. The sea level was lowered glacio-eustatically during the Thurnian 
and Baventian. In late Baventian times a local marine transgression in North Norfolk 
allowed the incursion of a marine fauna in which M. balthica is the most frequent species 
(Norton 1967). Deposits of 'Weybourne Crag' at Sheringham, Sidestrand, West Runton 
and grey shelly deposits withM. balthica in borings at Mundesley, represent this phase. 
The succeeding Pastonian was a time of regression on the North Norfolk coast, with de- 
position of thick estuarine silts. In these conditions the M. balthica stocks, with the rest 
of the 'Weybournian' fauna, retreated. Later Pastonian, and younger, 'Weybourne Crag' 
deposits on the North Norfolk Coast were formed by reworking of the primary Baven- 



NORTON and SPA INK 

TABLE 1 



35 



East Anglia Stages 






Netherlands Stages 


(Temperate Stages 


Pas de Calais Strait 


Macoma arrivals 


(Correlation 


italicised) 






not guaranteed) 


Pastonian 


Closed 


(reworking) 


Eburonian 


Baventian 


Closed 


M. balthica 


Eburonian 


Antian 


Closed 




Tiglian in nonmarine 
faciès 


Thurnian 


Closed 




Tiglian in nonmarine 
faciès 


Ludhamian (top) 


Closed 




Tiglian in marine faciès 


Ludhamian (lower)* 


Open 




Tiglian in marine faciès 


Butleyan Red Crag* 


Closed 




no pollen in Red Crag 


Newbournian Red Crag 


Open 


M. calcárea 


no pollen in Red Crag 


Waltonian Red Crag 


Open 


M. praetenuis 


no pollen in Red Crag 


Coralline Crag (Pliocene) 


Open 


M. obliqua 


Scaldisian 



*As mentioned in the text, the relationship between the Ludham Crag and Red Crag is not 
understood and this table should not be read either as correlating them, or as stating that the 
Pas de Calais Strait closed twice. 



200 kms 



West Runton 



Sidestrand 
Mundeslev 




NORTH 
NORFOLK 
COAST SITES 



SOUTHERN 
BASIN 



FIG. 1. Sketch-map of East Anglia showing the 2 main basins on the Crag base. 



36 PROC. FOURTH EUROP. MALAC. CONGR. 



tian material. The 'Weybourne Crag' deposits are diachronous. The Pastonian 
sea spread over the rest of the Northern Basin and Southern Basin. Silts alone were 
deposited in the Northern Basin. Mollusca were living in the Southern Basin. M. 
balthica has never been found in the shelly deposits here though the molluscan assem- 
blages at some sites (Norton 1970) show that conditions would have been suitable 
for it. Apparently this species had become locally extinct and did not recolonise 
after its short incursion in the Baventian. 

Some records of M. balthica in the Netherlands Pliocene or Early Pleistocene were 
published by Lorié (1885). Heering (1950) summarises them. This gave rise to the 
term 'Weybournien' for the top part of the 'Icenien' (Tesch 1942). Examination of 
these shells (Spaink & Norton 1967) shows that all are wrongly determined* They 
should be M. calcárea, M. obliqua or M. praetenuis. A few shells are correctly 
determined but belong to a much younger horizon mistakenly recorded as 'Icemen' . 
The use of the term 'Weybournien' in the Dutch succession has therefore been dis- 
continued, which is fortunate as we (op. cit.) have inferred that it cannot be placed 
later than Tiglian TC4c which is similar to the Thurnian in East Anglia whereas the 
East Anglia 'Weybourne Crag' is Baventian, Pastonian or Cromerian. 

After the brief occurrence of M. balthica in the East Anglia Pleistocene and the 
Pastonian and Cromerian reworking of its shells, follows the remainder of the Cromer 
Forest Bed Series and the first glaciation of this region, the Lowestoftian (which may 
be equivalent to the Elsterian). Following the Elsterian in the Netherlands, are founc 1 
the marine deposits of the Holsteinian Interglacial, in which M. balthica is abundant, 
as it has been in suitable deposits ever since. 

ACKNOWLEDGEMENTS 

We thank Dr R. G. West, whose palynological studies form the basis of the dating of 
the Crag Deposits mentioned, for kindly informing us of unpublished results of his 
work. 

REFERENCES 

FUNNELL, B. M., 1961, The Paleogene and Early Pleistocene of Norfolk. Trans. 
Norfolk Norwich natur. Soc, 19: 340-356. 

HEERING, J., 1950, The Pelecypoda (and Scaphopoda) of the Pliocene and older- 
Pleistocene Deposits of the Netherlands. Meded. Geol. Sticht. С, 4(1), no. 9. 

HOPKINS, D. M., 1967, Quarternary Marine transgressions in Alaska. Ch. 4. In: The 
Bering Land Bridge, ed. D. M. Hopkins, Stanford Univ. Press. 

LORIE, J., 1885, Resultats géologiques et paléontologiques des forages de puits à 
Utrecht, Goes et Gorkum (Contributions à la géologie des Pays-Bas I). Arch. 
Mus. Teyler, Sér. 2, vol. 2. 

MORONI, M. A., 1967, Notizie preliminari sulla macrofauna calabriana di Monte- 
scaglioso (Matera). Atti Accad. gioenia Sei. nat., Ser. 6, vol. 18. 

NORTON, P. E. P., 1967, Marine Molluscan assemblages in the Early Pleistocene of 
Sidestrand, Bramerton and the Royal Society Borehole at Ludham, Norfolk. Phil. 
Trans. Roy. Soc, В 155: 437-453. 

NORTON, P. E. P., 1970, The Crag Mollusca - a conspectus. Bull. Soc. belge GéoL 
Paléont. Hydrol., 79: 157-166. 

SPAINK, G. & NORTON, P. E. P., 1967, The stratigraphical range of Macoma balthica 
(L) [Bivalvia, Tellinacea] in the Pleistocene of the Netherlands and Eastern Eng- 
land. Meded. Geol. Sticht., N.S., 18. 



NORTON and S PA INK 37 

STRAUCH, F., 1963, Zur Geologie von Tjörnes (Nordisland). Sonderveröff eeol Inst 

Köln, 8. ' ' 

STRAUCH, F., 1970, Die Thule- Landbrücke als Wanderweg und Faunenscheide zwischen 

Atlantik und Skandik im Tertiär. Geol. Rdsch., 60: 381-417. 
TESCH, P., 1942, De Noordzee van historisch-geologisch standpunt. Meded Riiks 

Geol. Dienst, A. 9. 
VOORTHUYSEN, J. H. van, 1954, Crustal movements of the southern part of the North 

Sea during Pliocene and early Pleistocene times. Geol. en Mijnbouw, N.S., 16: 165. 



MALACOLOGIA, 1973, 14: 38 

PROC. FOURTH EUROP. MALAC. CONGR. 

PHYLOGENETICAL INVESTIGATIONS IN THE NEOGENE ASTARTIDAE 
OF THE SOUTHERN NORTH SEA BASIN 

Gerard Spaink 

Geological Survey of the Netherlands 
Haarlem, Holland 

ABSTRACT 

In the Pliocene deposits of the southern North Sea basin the family of Astartidae is an important group 
of Mollusca (Bivalvia) consisting of more than 15 species. These Astartidae can be divided into several 
taxonomical groups. In most of these groups the Astarte species can be arranged into pairs. The members 
of each pair have the same characters in contrast and one is always older than the other. The older 
member has a relatively thick, convex compressed and comparatively small shell, while the younger one 
has a relatively thin, flat and more oval shell, which is bigger. It follows that during the Pliocene epoch 
the Astartidae increased in size. 

The young form may be an adjusting form from the old form, following the constant decrease of average 
temperature during the Pliocene. At the end of the Pliocene the average temperature fell lower and the 
Arctic influence became stronger. All Neogene Astartidae in the southern North Sea basin died out rather 
suddenly, except those species which extended to the open Atlantic coast as well as inhabiting the southern 
North Sea basin. They were able to migrate to the South and they still occur in the Mediterranean and along 
the Atlantic coasts of Western Europe. Next the Arctic Astartidae were able to migrate to the South and 
occupy the southern North Sea basin with other taxonomical groups which have nothing to do with the 
Neogene groups. Although some of these Arctic species come close together morphologically, no radiations 
into pairs, as with the Neogene species, occur. 

A possible explanation of the cause of the radiation in the Neogene Astartidae is discussed. 

The point of view that the Neogene Astartidae occur in morphologically similar pairs has its conse- 
quences for the nomenclature. The members of the pairs should be named to reflect this. Instead of 
Astarte omalii and Astarte basteroti we should write Astarte omalii omalii and Astarte omalii basteroti, 
and so on. 






(38) 



MALACOLOGIA, 1973, 14: 39-46 

PROC. FOURTH EUROP. MA LAC. CONGR. 

MINERALOGY AND BIOGEOCHEMISTRY OF CALCAREOUS 
OPERCULI AND SHELLS OF SOME GASTROPODS 1 

O. S. Adegoke 

Department of Geology, University of Ife 
lie -If e, Nigeria 

INTRODUCTION 

The nature and structure of the operculum of gastropods and its probable equivalence 
to various other molluscan structures have received the attention of malacologists 
since Adanson (1757) first alluded to its homology with the second valve of pelecypods. 
Gray (1850) independently arrived at the same conclusion and, citing evidences based on 
morphology, mobility and growth pattern, he concluded that the operculum was a modi- 
fication of the other shell of the gastropod, analogous to the second valve of the pele- 
cypod, and secreted by the opercular mantle. 

The idea was revived in recent years by Duges (1829), Fleischmann (1932), who 
concluded that the operculum and shell are opposed organs, left and right, and also by 
Pruvot-Fol (1954) who regarded the operculum as a ventral replica of the gastropod 
dorsal valve, homologous to the byssus of pelecypods and the aptychus and anaptychus 
of some ammonites. 

Opponents of the suggested homology include Lamarck (1801), de Blainville (1825), 
Houssay (1884), Fischer (1940) and Kessel (1941). Unlike the proponents, the latter 
emphasized the distinctness in origin of the two structures - the shell being a product 
of the mantle while the operculum is produced by the foot - and their conclusions were 
grounded mainly on embryological and ontogenetic evidences (see especially Houssay, 
1884 and Kessel, 1941). 

In the present study, minéralogie and biogeochemical data are presented on the 
shells and the calcareous operculi of nineteen prosobranch species representing seven 
genera, Astraea, Turbo, Lunella, Nerita, Neritina, Puperita and Natica (see PI. 1 and 
Table 1). The study is significant in that it provides quantitative proof that major 
differences exist between the two structures. 

ANALYTICAL TECHNIQUES 

The analysed shells were initially leaned under a binocular microscope to remove 
all adhering epiphytes ana foreign inorganic particles. The specimens were crushed 
to increase the surface area and treated with commercial Clorox to remove the organic 
matrix. The residue was thoroughly washed, dried, ground by hand in a mortar and 
passed through a sieve with 100 meshes per inch. Large specimens were ground in 
their entirety, whereas two or more specimens of smaller shells were ground together 



1 Most of the analytical data reported here were obtained when the writer held a postdoctoral 
fellowship at the California Institute of Technology, Pasadena, California. The writer thanks 
Professor Heinz A. Lowenstam, Margaret Dekkers and Elizabeth Bingham. The specimens 
illustrated on Plate 1 were kindly supplied by Dr. Rosewater of the Smithsonian Institution, 
Washington, D. C. 

(39) 



40 



PROC. FOURTH EUROP. MALAC. CONGR. 
TABLE 1. Summary of analytical data 



Species 


Weight 
(gm) 


% Aragonite 


% Mg 


% Sr 


Shell 


Operculi 


Shell 


Operculi 


Shell 


Operculi 


Astraea longispina 


4.57 


100 


35 


0.01 


0.67 


0.16 


0.14 


(Bermuda) 


8.71 


100 


28 


0.01 


0.88 


0.15 


0.14 




12.42 


100 


26 


0.01 


0.91 


0.15 


0.13 




23.68 


100 


13 


0.01 


1.06 


0.16 


0.13 


Astraea undosa 


- 


100 


100 


0.02 


0.09 


0.15 


0.17 


(California) 


- 


100 


100 


0.03 


0.11 


0.14 


0.16 


Turbo setosus 


0.99 


100 


100 


0.01 


0.03 


0.14 


0.15 


(Palau) 


3.35 


100 


100 


0.01 


0.02 


0.16 


0.14 




5.12 


100 


100 


0.01 


0.01 


0.16 


0.14 


Turbo chrysostomus 


8.28 


100 


100 


0.01 


0.02 


0.16 


0.14 


(Palau) 


15.54 


100 


100 


0.01 


0.03 


0.16 


0.13 




21.42 


100 


100 


0.01 


0.01 


0.16 


0.14 




24.73 


100 


100 


0.02 


0.03 


0.14 


0.13 




25.99 


100 


100 


0.01 


0.03 


0.16 


0.12 




26.69 


100 


100 


0.01 


0.03 


0.14 


0.12 


Turbo argyrostomus 


31.59 


100 


100 


0.01 


0.03 


0.15 


0.14 


(Palau) 
















Lunella smaragda 


0.65 


100 


100 


0.01 


0.05 


0.15 


0.14 


(New Zealand) 


1.02 


100 


100 


0.01 


0.05 


0.17 


0.12 




2.29 


100 


100 


0.01 


0.06 


0.16 


0.16 


Nerita peloronta 


2.96 


68 


100 


0.32 


0.04 


0.18 


0.51 


(Bermuda) 


3.32 


71 


100 


0.32 


0.03 


0.18 


0.50 




4.34 


67 


100 


0.30 


0.03 


0.22 


0.50 


Nerita tessellata 


- 


56 


100 


0.49 


0.05 


0.16 


0.43 


(Bermuda) 


0.12 


54 


100 


0.48 


0.06 


0.17 


0.37 




0.46 


48 


100 


0.48 


0.05 


0.16 


0.37 




0.75 


51 


100 


0.46 


0.04 


0.17 


0.40 




0.89 


51 


100 


0.51 


0.08 


0.17 


0.43 




1.35 


64 


100 


0.39 


0.03 


0.17 


0.49 




1.46 


45 


100 


0.54 


0.04 


0.17 


0.41 




2.07 


75 


100 


0.26 


0.05 


0.18 


0.46 




2.43 


63 


100 


0.36 


0.05 


0.16 


0.36 




2.47 


62 


100 


0.39 


0.04 


0.16 


0.45 




3.16 


70 


100 


0.28 


0.03 


0.16 


0.45 


Nerita albicilla 


3.35 


76 


100 


0.27 


0.05 


0.18 


0.31 


(Palau) 


3.41 


72 


100 


0.27 


0.05 


0.16 


0.31 




3.47 


69 


100 


0.34 


0.05 


0.17 


0.31 


Nerita polita 


8.18 


75 


100 


0.35 


0.03 


0.20 


0.40 


(Palau) 


11.22 


73 


100 


0.30 


0.05 


0.17 


0.39 


Nerita plicata 


0.13 


63 


100 


0.55 


0.04 


0.18 


0.36 


(Palau) 


0.18 


64 


100 


0.51 


0.04 


0.19 


0.38 




0.23 


66 


100 


0.58 


0.05 


0.23 


0.38 




0.28 


67 


100 


0.45 


0.04 


0.15 


0.33 



ADEGOKE 



41 



Table 1 (cont. ) 



Species 


Weight 
(gm) 


% Aragonite 


%Mg 


% 


Sr 


Shell 


Operculi 


Shell 


Operculi 


Shell 


Operculi 


Nerita plicata 


1.24 


73 


100 


0.31 


0.03 


0.19 


0.45 




1.39 


77 


100 


0.41 


0.04 


0.23 


0.46 




2.25 


70 


100 


0.39 


0.04 


0.17 


0.44 




2.40 


64 


100 


0.44 


0.04 


0.22 


0.45 




2.46 


73 


100 


0.34 


0.04 


0.16 


0.48 




3.86 


73 


100 


0.35 


0.04 


0.17 


0.46 


Nerita picea 


1.12 


68 


100 


0.58 


0.05 


0.21 


0.42 


(Palau) 


2.51 


73 


100 


0.38 


0.05 


0.22 


0.40 




5.58 


78 


100 


0.30 


0.05 


0.25 


0.46 


Nerita senegalensis 


- 


79 


100 


0.02 


0.08 


0.15 


0.18 


(Nigeria) 
















Neritina sp. 


0.08 


94 


100 


0.01 


0.04 


0.23 


0.76 


(Palau) 


0.64 


96 


100 


0.01 


0.02 


0.25 


0.64 




0.73 


97 


100 


0.01 


0.02 


0.29 


0.52 


Puperita pupa 


0.12 


93 


100 


0.04 


0.07 


0.16 


0.31 


(Grand Cayman) 


0.15 


95 


100 


0.06 


0.07 


0.17 


0.27 




0.19 


92 


100 


0.04 


0.07 


0.18 


0.27 




0.22 


94 


100 


0.05 


0.08 


0.16 


0.30 




0.23 


94 


100 


0.04 


0.09 


0.16 


0.30 




0.32 


94 


100 


0.05 


0.07 


0.18 


0.28 




0.37 


95 


100 


0.05 


0.06 


0.16 


0.27 






93 


100 


0.05 


0.06 


0.17 


0.30 



to obtain powders large enough for analyses. 

A representative portion of the sieved sample was removed for analyses. Aragonite 
percentages were determined by X-Ray diffraction as described by Lowenstam (1954). 
Percentage strontium and magnesium were estimated by the emission spectrograph^ 
and X-ray fluorescence techniques as described by Lowenstam (1961). 

RESULTS AND DISCUSSION 



The analytical results are shown in Table 1. No attempt is made to convert the Mg 
and Sr values to parts per million or to estimate mole percent of the carbonate because 
the study is interested merely in comparing the relative proportions between shell 
and operculum. Average values were used to plot the graphs shown in Figures 1 and 2. 

Mineralogy 

It has long been established that molluscan shells are either entirely aragonitic or 
composed of varying proportions of calcite and aragonite. The aragonite-calcite ratio 
is primarily affected by temperature, less so by the physiology of the organism and 
water chemistry (see Lowenstam, 1960). The effects of these factors on the values 
shown in Table 1 have been largely offset by comparing values for shells and operculi 
of the same individuals. 

As emphasized by Kessel (1941), the operculum is largely aragonitic (see Fig. 1). 



42 



PROC. FOURTH EUROP. MALAC. CONGR. 










11 




15 16 




PLATE 1 

FIGS. 1, 2. Turbo setosus, XI. FIGS. 3, 4. Turbo chrysostomus, XI. FIGS. 5-7. Astraea 
undosa. 5, shell XI; 6, 7, operculum X 2. FIGS. 8-11. Astraea longispina . 8, shell XI; 11 , 
operculum X 2; 9, 10, polished section of operculum showing dominantly calcitic initial portion 
X 4. FIGS. 12, 13, Lunella smaragda . 12, shell XI; 13, operculum X 2. FIGS. 14-16. 
Nerita peloronta. 14, shell X 1; 15, 16, operculum X 2. 



ADEGOKE 



43 



Species 

Astraea longi spina 
Astraea undosa 
Turbo setosus 
Turbo chrysostomus 
Turbo argyrostomus 
Lune/ /a smaragda 
Nerita peloronta 
Nerita tessellata 
Nerita albicil/a 
Nerita pol i ta 
Nerita plicata 
Nerita picea 

Neritina sp. 
Puperita pupa 



% Aragon ¡te %Mg 

50 100 0.5 



0.30 0.60 

I L 






FIG. 1. Graph showing Aragonite, Magnesium and Strontium contents of the shells and operculi 
of the species analysed. 

The only exception in this study is that of Astraea longispina which is dominantly 
calcitic (Figs. 1, 2). The proportion of calcite was found to increase directly with age 
(Figs. 2C, 2D), attaining a maximum of about 87% in the largest analysed specimen. 
The shell is, however, entirely aragonitic (Fig. 2C). 

The neritids analysed {Nerita, Neritina and Puperita) were equally significant. The 
shell is bimineralic with varying proportions of calcite and aragonite (Fig. 1). The 
operculi, however, uniquely have 100 percent aragonite. These two groups conclusively 
show that gross physiological differentiation, demonstrated by minéralogie differences, 
exists between the secretions of the mantle and foot of the same gastropod. 

Astraea undosa, Natica, the species of Turbo and the closely related Lune lia have 
monomineralic shell and operculum. 

Magnesium content 

The biogeochemistry of Magnesium was discussed in detail by Chave (1954) and was 
aptly summarized by Lowenstam (1960). Both support a minéralogie control of Mg 
content in which the calcitic structure accommodates a considerably larger amount of 
Magnesium in solid solution than the aragonitic structure. Turekian and Armstrong 
(1960), however, contended that generic affinity is more important than crystal form. 



44 



PROC. FOURTH EUROP. MALAC. CONGR. 



OPERCULUM 
ШШЩ SHELL 
-i 0.20t 




GROWTH 



GROWTH — 




OPERCULUM 



GROWTH 



i 20 25 

WEIGHT (GM) 



FIG. 2. Analytical data on Astraea longispina showing: A, Mg content, B, Sr content and C, 
Aragonite content of shells and operculi relative to age. D, Graph showing the inverse relation- 
ship between aragonite content of the operculum of A . longispina and the growth stage. 



The major differences in Mg values recorded in the bimineralic species studied 
here can be directly correlated with differences in mineralogy (see Fig. 1). For 
example, the entirely aragonitic shell of Astraea longispina shows a Mg content of 
about 0.01 percent whereas the dominantly calcific operculum of the same specimens 
show a range between 0.67 and 1.06 percent (Fig. 2A). The completely aragonitic 
neritid operculum, by contrast, shows a low Mg content (0.02-0.09 percent), whereas 
their calcific shells show a range between 0.26 and 0.58 percent. In both Neritina 
and Puperita with low calcite content (3-8 percent) in the shell, the Mg value is com- 
parably low in shell and operculum. 

These results indicate that the Mg content is influenced more by mineralogy than 
generic affinity. 

The entirely aragonitic species offer better examples for studying the biogeochemical 
differences between shell and operculi. Though the Mg content of both structures is 
expectedly low, the operculi consistently show higher Mg values than the shells (see 
Fig. 1). 

Strontium content 

The Strontium content of calcareous shells is, in general, affected by the same fac- 
tors which influence the Mg content. The effect of the crystal form is different in 
that the aragonitic structure accommodates more Sr in solid solution than the calcific 
structure (Odum, 1957; Lowenstam, 1960). Turekian and Armstrong (1960), however, 



ADEGOKE 45 

favored generic control. 

Among the neritids, the aragonitic operculi show higher Sr values (0.27-0.76 percent) 
than the calcite -bearing shells (0.15-0.29 percent), thus substantiating Odum's 
(op. cit.) and Lowenstam's (op. cit.) views. The fact that the operculum of Neritina 
and Puperita have almost twice as much Sr as the shell despite the low calcite content 
(3-8 percent) of the latter, coupled with the virtually identical Sr content of the ara- 
gonitic shells and the dominantly calcitic operculi oí As trae a longispina (see Table 1) 
indicate that generic affinity may be as important as crystal form in the distribution 
of Sr. 

SUMMARY 

Though the suggested homology of operculi and shells of gastropods and the sup- 
posed equivalence of both to the valves of pelecypods is no longer accepted, little 
quantitative data have been published on the subject. Nineteen calcareous operculi - 
secreting prosobranch species representing seven genera (Astraea, Turbo, Lunella, 
Nerita, Neritina, Puperita and Natica) were examined minerallogically by X-ray 
diffraction and biogeochemically by X-ray fluorescence and emission spectrographic 
methods. The results confirm the existence of major differences between the two 
structures. 

The operculi (except that of Astraea longispina) shows 100 percent aragonite even 
when the associated shell contains a fair proportion of calcite. 

Strontium concentration is consistently lower in shells (0.13-0.23%) than in operculi, 
with the highest concentrations (0.31-0.76%) occurring in the neritid operculi. Mag- 
nesium concentration is, on the average, lower in shell (0.01-0.08%; 0.26-0.58% in 
calcite-bearing neritid shell) than in operculi (0.01-0.11%). The highest concentration 
of 0.67-1.06% was recorded in the calcite-bearing operculi of Astraea longispina. 

The data support a minéralogie control of Mg content as proposed by Chave (1954) 
and Lowenstam (1960) but contradict the generic control supported by Turekian and 
Armstrong (1960). The Sr content, however, seems equally influenced by both factors. 

REFERENCES 

ADANSON, M., 1757, Histoire naturelle du Senegal. Coquillages. Paris. 275 p, 19 pis., 

1 map. 
CHAVE, К. E., 1954, Aspects of the biogeochemistry of magnesium; (1) Calcareous 

marine organisms. J. Geol., 62: 266-283. 
de BLAINVILLE, H. M., 1825, Manuel de Malacologie et de Conchyliologie. Paris. 
DUGES, A., 1829, Observations sur la structure et la formation de l'opercule chez les 

Gastéropodes pectinibranches. Ann. Sei. natur. (Zool.), 18: 113-133. 
FISCHER, P-H., 1940, Sur l'idée d'homologie de la coquille et de l'opercule chez les 

Gastéropodes; données embryologiques. Cr. hebd. Séanc. Acad. Sei. Paris, 211: 

515-517. 
FLEISCHMANN, A., 1932, Vergleichende Betrachtungen über das Schalenwachstum der 

Weichtiere (Mollusca). H. Deckel (Operculum) und Haus (Concha) der Schnecken 

(Gastropoda). Z. Morph. Ökol. Tiere, 25: 549-622. 
GRAY, J. E., 1850, On the Operculum of Gasteropodous Mollusca, and an attempt to 

prove that it is homologous or identical with the second valve of Conchifera. Ann. 

Mag. natur. Hist., 5, 2nd ser: 476-483. 
HOUSSAY, F., 1884, Recherches sur l'opercule et les glandes du pied des gastéropodes. 

Arch. Zool. exp. gen., 2nd ser., 2: 171-288. 
KESSEL, E., 1941, Über bau und bildung des prosobranchierdeckels. Z. Morphol. 



46 PROC. FOURTH EUROP. MALAC. CONGR. 

Ökol. Tiere, 38: 197-250. 
LAMARCK, J. B. de, 1801, Systeme des animaux sans vertebres. Paris. 
LOWENSTAM, H. A., 1954, Factors affecting the Aragonite: Calcite ratios in car- 
bonate-secreting marine organisms. J. Geol., 62: 284-322. 
LOWENSTAM, H. A., 1960, Paleoecology (geochemical aspects). McGraw-Hill 

Encyclopedia of Science and Technology, 516-518. 
LOWENSTAM, H. A., 1961, Mineralogy, О 18 . О 16 ratios, and strontium and magnesium 

contents of Recent and fossil brachiopods and their bearing on the history of the 

oceans. J. Geol., 69: 241-260. 
ODUM, H. T., 1957, Biogeochemical deposition of strontium. Publ. Inst. Mar. Sei. 

Univ. Texas, 4: 38-114. 
PRUVOT-FOL, ALICE, 1954, Le bulbe buccal et la symétrie des mollusques. H. Arch. 

Zool. exp. gen., 91: 235-330. 
TUREKIAN, K. K. & ARMSTRONG, R. L., 1960, Magnesium, strontium and barium 

concentrations and calcite-aragonite ratios of some Recent Mollusca Shells. J. 

mar. Res., 18(3): 133-151. 



MALACOLOGIA, 1973, 14:47-51 

PROC. FOURTH EUROP. MALAC. CONGR. 

TRANSFERT DU CALCIUM A TRAVERS L'EPITHELIUM DU REPLI 
OPERCULAIRE CHEZ ASTREA RUGOSA L. (TURBINIDAE) 

Jean Vovelle 

Histologie et cytologie des Invertébrés marins 
Université de Paris VI, France 

Le "repli operculaire" qui peut recouvrir aux deux tiers l'opercule calcifié du 
Gastéropode Astrea rugosa (Turbinidae) apparaît comme un matériel histologique 
favorable pour démontrer l'évidence du transfert de calcium à travers une partie de 
son epithelium. Des travaux antérieurs nous ont familiarisé avec le problème de la 
composante protéique tannée de l'opercule des Prosobranches et nous savons qu' Astrea 
en donne une variante intéressante par son opercule oligogyre sous-jacent à la galette 
aragonitique dont l'élaboration nous retient présentement. Mais si la zone de l'épithê- 
lium pédieux dorsal immédiatement antérieure à la surface d'insertion du disque 
operculigère révèle une chimie spécifique où l'on peut démontrer les composantes 
protéique, aromatique et phénolasique de la lame organique inférieure, la zone en 
croissant réfléchi qui la précède vers l'avant de l'animal, cette face interne, concave, 
du repli operculaire, ajustable au front de croissance de l'opercule calcaire, est 
logiquement seule concernée par la traversée d'un calcium que nous allons reconnaître 
comme labile, sous forme soluble, et que par conséquent les techniques histochimiques 
courantes échouent à mettre en évidence. Le recours à divers artifices d'histochimie 
et de radioautographie à l'échelle de la microscopie photonique ou électronique, ou 
d'histoenzymologie, permet de tourner la difficulté et de marquer les étapes de son 
passage. 

HISTOCHIMIE 

On a pratiqué dans un premier temps sur coupes à la paraffine de pièces fixées 
par les liquides appropriés (alcool-chloroforme, alcool-formol selon la formule de 
Me Gee Russell) les techniques les plus classiques de détection du calcium ionique 
insoluble: aux métaux lourds (Stoelzner, Von Kossa), aux laques (purpurine, rouge 
nucléaire solide et alizarine selon les protocoles de Me Gee Russell), au rhodizonate 
de sodium. Leur réponse est toujours négative, sauf parfois pour indiquer une légère 
pellicule apicale superficielle dans les plissements de 1' epithelium de la face concave 
du repli. Cette réponse négative est tout à fait cohérente avec celle que l'on connaît 
au niveau des territoires de 1' epithelium palléal impliqués dans la sécrétion de la 
fraction minérale de la coquille. 

La technique récente de Kashiwa (1966) au Glyoxal bis (2. hydroxy anil) (=GBHA) 
permet d'envisager la chelation du calcium soluble sous réserve qu'il soit maintenu 
totalement ou partiellement en place par les techniques préliminaires. Pratiquée sur 
coupes au cryostat de tissus frais elle donne une réponse positive dans toute la zone 
conjonctive sous -epitheliale du repli operculaire, sous forme de traînées intensément 
colorées, et se retrouve plus discrètement soulignant la bordure en brosse de l'épi- 
thélium. 

Puisqu'il s'agit évidemment de calcium ionique soluble, dont l'emploi de la micro- 
incinération, pratiquée sur coupes au cryostat de tissus frais, assure, au niveau même 
de l'épithélium, la présence dans des spodogrammes trop grossiers pour apporter des 
indications supplémentaires, on aurait pu imaginer le recours aux techniques de 
précipitation par l'acide oxalique pour sa caractérisation ultérieure. Décevant en 

(47) 



48 



PROC. FOURTH EUROP. MALAC. CONGR. 



5mm 



5ц 



caud. 






FIG. 1. A, Coupe sagittale de la zone dorsale operculigère du pied; bpp: bourrelet palleal 
postérieur; col: région columellaire; caud: région caudale; oc: opercule calcaire; ot: opercule 
protéique tanné; ro: repli operculaire. B, Détail de la région antérieure columellaire et du 
repli operculaire; eot: epithelium sécréteur de l'opercule protéique tanné; fe: face externe 
pigmentée du repli operculaire; fi: face interne sécrétrice de l'opercule calcaire; ls: lacunes 
sanguines. C, Organisation ultrastructurale d'une cellule de la face interne du repli operculaire; 
b: basale; cm: corps multivésiculaires; gp: granulations pigmentaires ; je: jonction cloisonnée; 
mg: microvillosités; za: zonula adhaerens . 



microscopie optique le procédé connaît un certain succès dans sa transposition en 
microscopie électronique (Carasso et Favard-1966; Kniprath-1971) lorsqu'il s'agit 
d'animaux dulçaquicoles mais son usage pour notre matériel marin était d'emblée 
aléatoire. 

Nous avons préféré nous adresser à la transposition électronique d'une technique 
aux métaux lourds (acétate de Pb, cf. Carasso et Favard-1966) dont l'intérêt essentiel 
est de procéder à une substitution sur pièce, préalable aux procédures de déshydratation 
et d'enrobage, et par conséquent de fournir un état meilleur de conservation en place 
du métal substitué, observable à l'échelle ultrastructurale. Nous avons suivi le 
protocole des auteurs précités, et observé sur microscope Hitachi HS 7 et U 11 В des 
coupes ultraminces avec ou sans post-coloration selon la formule de Reynolds. La 
post-coloration permet de retrouver des images plus satisfaisantes et plus proches 
du plan d'organisation cytologique (dont nous avons déjà rendu compte par ailleurs), 
en éliminant un fin précipité généralisé d'ailleurs significatif. Les localisations plus 
massives qui subsistent dans ces conditions concernent un précipité important entre 
les microvillosités de la bordure en brosse, des dépôts en réservoirs dilatés au niveau 
de la portion subapicale des espaces intercellulaires, caractérisée par sa zonula 
adhaerens et ses jonctions cloisonnées, et des dépôts plus discrets mais réguliers 



VOVELLE 49 

dans toute la partie inférieure des espaces intercellulaires, jusqu'à la basale et au 
conjonctif sous-jacents qui présentent par endroits des accumulations considérables 
du métal substitué. 

RADIOAUTOGRAPHIE 

Le recours aux techniques de radioautographie a été développé à partir de l'emploi 
du Ca 45, utilisé sous forme de chlorure et injecté dans la région dorsale du pied en 
solution aqueuse à 20 mC/mg d'activité spécifique (la taille des animaux et la précarité 
de l'installation empêchent d'ajouter, comme Istin et coll. -1970, l'élément marqué au 
milieu ambiant). Après une survie de deux jours l'animal est sacrifié et la pièce 
fixée suivant les cas pour la microscopie optique à l'alcool formol, ou, pour la micro- 
scopie électronique, soit à la glutaraldéhydeà3p.l00 dans le tampon phosphate à pH7, 
soit suivant la technique à l'acétate de plomb de Favard et Carasso. Les images 
obtenues en microscopie photonique ont le mérite de souligner la dissymêtrie des 
deux versants externe et interne du repli operculaire. La seule face interne présente 
une réponse importante dans le conjonctif sous-jacent et, très intensément, au niveau 
de la bordure en brosse epitheliale. L'itinéraire suggéré dans le conjonctif est moins 
superficiel que l'étape terminale indiquée par la méthode histochimique au GBHA et, 
sur des images d'exposition suffisante, certaines cellules conjonctives apparaissent 
renforcées. 

Les quelques images obtenues en microscopie électronique doivent leur rareté à la 
nécessité imprévue d'une longue exposition (2 mois et demi) et les impacts radioactifs 
observables concernent essentiellement les zones de jonction intercellulaires sub- 
apicales de 1' epithelium du repli interne: dans quelques cas elles se superposent 
précisément aux corps multivésiculaires abondants à leur voisinage. 

HISTOENZYMOLOGIE 

L'histoenzymologie des phosphomonoestérases a le double mérite de nous proposer 
l'existence de processus enzymatiques impliqués dans ce transfert du calcium et de 
différencier grâce à eux formellement les deux faces externe et interne du repli 
operculaire, suivant une ligne de séparation dont la radioautographie en microscopie 
photonique suggérait déjà l'importance. 

La recherche des phosphomonoestérases alcalines non spécifiques a donné des 
résultats convergents par les deux méthodes utilisées (de Gomori au nitrate de cobalt 
et de Pearse aux colorants azoiques couplés) sur coupes à la paraffine ou au cryostat 
avec légère post -fixation formolée. Elle correspond à une réponse positive élective 
au niveau de la bordure en brosse apicale de Г epithelium de la seule face concave du 
repli, alors que la face externe reste réfractaire. 

L'adênosine triphosphatase, démontrée par les deux méthodes de Wachstein et 
Meisel et de Padykula et Herman sur coupes au cryostat avec légère post -fixation 
formolée fournit une réponse superposable à la précédente, qui se complète dans la 
zone apicale sous-jacente à la bordure en brosse par la mise en évidence d'un système 
supplémentaire de granulations. Elles seules subsistent dans les contre -épreuves, 
notamment par mise en oeuvre du 2-3-dimercapto-l-propanol (BAL) qui bloque l'ac- 
tivité phosphatasique non spécifique de la bordure en brosse. On a pu supposer leur 
rapport avec les structures mitochondriales, mais les images de ces organites qu'on a 
pu leur superposer, fournies tant par la microscopie photonique (fuchsine d^'Altmann), 
que par la microscopie électronique, concernent également, bien qu'à un degré moindre, 
la région basale de la cellule epitheliale. Exclusivement apicales, deux catégories 
de formations restent à considérer comme support de l'ATPase: les formations 



50 



PROC. FOURTH EUROP. MALAC. CONGR. 




(+) 
















+ + 


+ + 


+ + 




+ 








+ 




+ 




+ 






(+) 

(inter- 
cell ulaire) 












+ 


+ 


+ 










+ 




+ 














+ 









Stoelzner GBHA Acétate RAG RAG Phospha- ATPase 

Alizarine de Pb photon, électron. tase 

électron. alcaline 

FIG. 2. Tableau interprétatif du passage du calcium au niveau de l'épithelium de la face interne 
du repli operculaire. 

sphérulaires "pigmentaires" (à conchoporphyrine), bien plus rares au niveau de la 
face interne de répithélium que dans sa face externe, et les "corps multivêsiculaires" 
signalés par le microscope électronique. 

Malgré les images imparfaites qu'elle nous a fournies, la transposition ultrastruc- 
turale de la technique de Wachstein et Meisel confirme la mise hors de cause des 
mitochondries et semble impliquer de préférence les corps multivésiculaires. 

CONCLUSION 



En somme, dans le domaine de Phistochimie et de la radioautographie, aussi bien 
à l'échelle photonique qu'électronique, les images que nous avons pu obtenir, toutes 
dépendantes de conditions diverses du maintien en place préalable d'un calcium 
prioritairement sous forme ionique soluble, fournissent des états plus ou moins 
satisfaisants, mais qui se manifestent heureusement comme des jalons complé- 
mentaires. 

Le tissu conjontif sous-jacent, jusqu'à la basale de l'épithelium de la face interne 
du repli, affirme son rôle de vecteur et assure l'origine endogène de la substance 
minérale. L'amorce d'une précipitation de cette dernière apparait dans les intervalles 
des microvillosités de la bordure en brosse de cet epithelium particulier: on est 
assurés d'ailleurs de la présence de Phosphomonoesterase alcaline non spécifique à 
ce niveau. Entre les deux, la traversée de l'épithelium proprement dit privilégie, à 
l'échelle untrastructurale, les espaces intercellulaires jusqu'aux dispositifs de jonction 
sub-apicaux. Ces données, cohérentes avec ce qu'on sait du transport des liquides à 
travers les epitheliums (cf. Diamond et Torney-1966), sont comparables à celles par 
exemple que Neff a fourni récemment à propos des glandes calcifères d'un Serpulidé. 



VOVELLE 51 

Au niveau de la zone apicale sous microvillositaire de Г epithelium des corps multi- 
vêsiculaires ou des formations vacuolaires interviennent, qui elles aussi peuvent 
rappeler les images de Neff ou de Kniprath, et qui dénoncent l'ultime transport actif 
du calcium sécrété. 

SUMMARY 

The "opercular fold" of Astrea rugosa secretes the calcareous piece overlying the 
protein operculum. Only epithelium of the internal opercular surface is crossed by the 
labile calcium ions. Presence of the calcium cannot be detected using standard histo- 
chemical techniques. The specific technique of Kashiwa using GBHA shows localization 
of soluble calcium at the level of the epithelial brush border, as well as on the basal 
lamina and the underlying connective tissue. The lead acetate staining method for elec- 
tron microscopy also demonstrates the presence of calcium, implicating the intercellu- 
lar spaces up to their subapical junction and finding again the accumulations at the level 
of the basal lamina, just as the precipitates on the microvilli. The use of calcium 45 
for radioautography in photonic microscopy illustrates the role of the vehicle of the con- 
nective tissue and the elective elimination of the cation at the level of the epithelial 
brush border of only the internal side. The histoenzymological research of the non- 
specific phosphomonoesterases and of the ATPase also allows us to detect this precisely 
defined region. Radioautography at the level of ultrastructures marks out the final ac- 
tive transfer of calcium in the apical zone under microvilli of this privileged epithelium. 

BIBLIOGRAPHIE 

CARASSO, N. & FAVARD, P., 1966, Mise en évidence du calcium dans le myonèmes 

pédonculaires de Ciliés Péritriches. J. Microsc, 5: 759-770. 
DIAMOND, J. M. & TOURMEY, J. Me D., 1966, Role of long extracellular channels in 

fluid transport across epithelia. Nature, 210: 817-818. 
ISTIN, M., 1970, Rôle du manteau dans le métabolisme du calcium chez les Lamel- 
libranches. B.I.S.T. (Commissariat à l'Energie atomique), 144: 53-80. 
KASHIWA, H. K., 1966, Calcium in cells of fresh bone stained with Glyoxal bis (2- 

hydroxyanil). Stain Technol., 41(1): 49-56. 
KNIPRATH, E., 1971, Cytochemische Lokalisation von Kalzium in Mantel epithel von 

Lymnea stagnalis (Gastropoda). Histochem., 25: 45-51. 
NEFF, J. M., 1971, Ultrastructural studies of the secretion of calcium carbonate by 

the Serpulid Polychaete worm Pomatoceros coeruleus. Z. Zellforsch, mikrosk. 

Anat., 120(2): 160-186. 
VOVELLE, J., 1969, Elaboration de la matière operculaire chez Tricolia pullus (L.), 

Gastropoda, Prosobranchia. Malacologia, 9(1): 293-294. 
VOVELLE, J., 1969, Complexity of the opercular materials in Astralium rugosum 

(Linné) (Gastropoda Prosobranchia, Turbinidae). Proc. malacol. Soc. Lond., 

38(6): 557. 
VOVELLE, J., 1969, Données histochimiques et cytologiques sur l'élaboration de 

l'opercule chez les Turbinidae. Bull. Soc. zool. Fr., 94(3): 501. 



MALACOLOGIA, 1973, 14: 53-61 

PROC. FOURTH EUROP. MALAC. CONGR. 

MANTLE ACTIVITY FOLLOWING SHELL INJURY IN THE 
POND SNAIL LYMNAEA STAGNALIS L. 

Lucy P. M. Timmermans 

Zoological Laboratory, University of Utrecht, The Netherlands^- 

ABSTRACT 

Histological and histochemical studies were carried out on the mantle of 
Lymnaea stagnalis at various intervals after a shell defect. 

In the mantle area underlying the damaged shell area, the epithelial cells 
become elongated and show an increased content of RNA and alkaline phosphatase. 
At first (3 and 5 days after a shell defect), the stimulated area is considerably 
larger than the exposed region. Afterwards (8-16 days) the area of activated 
epithelium is restricted to the exposed mantle area. Peroxidase is demonstrated 
in the exposed mantle epithelium and in the repaired shell membrane. 

These results indicate that the mantle epithelium plays an important role in 
shell repair. The appearance of peroxidase in the exposed mantle epithelium 
and in the repaired shell points to the formation of tanned periostracum proteins 
after shell damage. 

INTRODUCTION 

During normal growth of snails, the increase in mantle area is coupled with an 
increase in shell area. It is now generally accepted that the shell is to be considered 
as a secretion product of the mantle, especially the mantle border, and that each layer 
of the shell is secreted by a definite region of the underlying mantle. 

In the mantle border of Lymnaea stagnalis (Fig. 1) a few sharply defined zones can 
be distinguished in the outer epithelium with histochemical methods for RNA, alkaline 
phosphatase and peroxidase (Timmermans, 1969). The high content of RNA in zones 
1 and 2 indicates that these areas are involved in protein synthesis, required for the 
formation of the periostracum. It is assumed that the enzyme peroxidase, which is 
present in this region only, plays a part in the tanning of periostracum proteins. The 
RNA in zone 3 may be involved in the formation of the inner layer of the periostracum. 
The formation of the calcareous layers is ascribed to zones 4 and 5. These zones, but 
not the periostracum-forming cells of zones 1-3, contain the enzyme alkaline phos- 
phatase which therefore is assumed to play a role in calcium deposition. Next to al- 
kaline phosphatase this region contains glycogen, carbonic anhydrase, ATP-ase and 
enzymes of the citric acid cycle, but not RNA and peroxidase. 

Generally, damage to the shell is followed by repair of the damaged region. However, 
it is still an unsolved question whether the periostracum is repaired, when a shell 
defect is not in contact with the mantle border. According to Simroth & Hoffmann 
(1928), Kessel (1933) and others, the periostracum in Gastropods is not repaired. On 
the other hand, Beedham (1965) reports that inlamellibranchiates a true periostracum 
is repaired after damage to the shell. 

Repair of a shell defect is carried out by the mantle, and it may be assumed that 
during shell repair the mantle tissue, underlying the damaged area, shows an increased 
activity. The increased activity might be manifested by an enlargement of the epi- 
thelial cells underlying the damaged shell area and by an increased enzyme activity 
in these cells. It is also possible that amoebocytes play an important role in shell 



1 Present address: Zoological Laboratory, Agricultural University, Wageningen, The Netherlands. 

(53) 



54 



PROC. FOURTH EUROP. MALAC. CONGR. 





FIG. 1. Transverse section through the mantle of Lymnaea stagnalis to illustrate the localiza- 
tion of the chemical compounds and enzymes. Zone 1 + 2, RNA, peroxidase; Zone 3, RNA; 
Zone 4, alkaline phosphatase; Zone 5, alkaline phosphatase, glycogen, carbonic anhydrase, 
ATP-ase, cytochrome oxidase, succinate dehydrogenase (and other dehydrogenases). 

FIG. 2. Shell of Lymnaea stagnalis, schematic drawing to illustrate the location of the frag- 
ments. 2,4,5, removed shell fragments; 1,2,3, (dotted line): mantle segment, used for histo- 
logical and histochemical examination. 

repair by carrying repair material to the damaged region (Wagge, 1951; Abolins- 
Krogis, 1963, 1968). If the periostracum is not repaired, particularly those enzymes 
will show an increased activity which are concerned with calcium secretion, as the 
calcium layers only contain a small amount of organic matrix. If, on the other hand, 
a periostracum is actually repaired, the appearance of compounds and enzymes can 
be expected which are involved in the formation of periostracum proteins. These 
considerations made it desirable to investigate : 1„ whether the epithelial cells under- 
lying the damaged shell area become enlarged; 2. whether the amounts of RNA and 
alkaline phosphatase increase; 3. whether peroxidase is present. A positive reaction 
for peroxidase may be an indication that the periostracum is repaired, whereas a 
negative peroxidase reaction may mean that no periostracum material has been formed. 

MATERIAL AND METHODS 



For the experiments snails of the same age (4 months) were used, which had been 
reared in the laboratory. Shell-fragments of 0.5 -0.6 cm- were removed with a 
dentist drill. The fragments were selected from the border of the shell and from areas 
to which the mantle edge could not be retracted (Fig. 2). 

At intervals from one hour to 21 days after the removal of the shell -fragments 
snails were anaesthesized (Joosse and Lever, 1959) and segments of the mantle were 
excised for fixation as shown in Fig. 2 (dotted line). The slices consist of mantle 
border (1), tissue from below the removed shell area (2) and the tissue in between 
both mantle areas (3). Equivalent mantle segments of control snails were used for 
comparison. 

Mantle slices were fixed at 1, 2, 3, 5, 24 hours and at 3, 5, 7, 8, 12, 15, 16 and 21 
days after inflicting shell damage. After each period at least three experimental 
snails and three control snails were used. The height of the epithelium was measured 
with an ocular micrometer. 

The mantle slices were freeze-dried or fixed in acetone at 4° С followed by em- 
bedding in paraffin. Also fixation in formol-calcium at 4° C, followed by cryostat 
sectioning has been applied. The sections were stained with hemalum eosin for histo- 
logical examination and with methylgreen-pyronin (Brächet, 1953) for the detection 
of RNA. The azo dye method of Pearse (1960, 1968) was used for the demonstration 
of alkaline phosphatase; the activity of peroxidase was investigated with the benzidine 
blue method (v. Duyn, 1955) after formalin fixation and cryostat sectioning. 



TIMMERMANS 



55 



TABLE 1. Size of cells and content of RNA, alkaline phosphatase and peroxidase in the mantle 
epithelium underlying a damaged shell area. 



Time after 


Height of 


cell in \x 


RNA 


Alkaline 


Phosphatase 


Peroxidase 


shell damage 














in days 


exper. 


control 


exper. control 


exper. 


control 


exper. control 


3 


8-12 


6-8 


+/++ tr 


tr/+ 


+ 




5 


15-18 


6-8 


++/+++ tr 


++ 


+ 




7/8 


24-30 


6 


-H-+ tr 


++ 


tr 




12 


24-30 


6-8 


+-H-/H-M' tr 


+++ 


tr 


++ 


15/16 


24-32 


6-8 


+++ tr 


++ 


+ 


++ 


21 


20-30 


6-8 


++/+++ tr 


+/++ 


tr 





+-НЧ- 



intense reaction 



+-H- 

++ distinct reaction 

+ moderate reaction 

tr weak reaction 



Acetone fixation followed by paraffin embedding was preferred as routine method 
for the detection of RNA and alkaline phosphatase, as with this method clear and 
comparable histological pictures were obtained from the long slices of mantle tissue* 
Although the alkaline phosphatase activity may be slightly less after acetone fixation, 
the same distribution pattern was obtained as in freeze-dried or cryostat sections, 
though incubation periods had to be prolonged. The peroxidase method was only 
carried out at 12-16 days after damage of the shell. 



RESULTS 



Repair of the damaged shell area 



After removing a marginal portion of the shell (Fig. 2, nr. 4 or 5) the snail retracted 
the mantle border up to the damaged area, where new shell material was added. After 
a few days the removed part was completely replaced. The removed portion was re- 
stored more rapidly than an equivalent area of normal shell was formed. When a 
fragment of shell was removed so far from the edge that it was impossible for the 
snail to retract the mantle border up to the damaged area (Fig. 2, nr. 2), repair also 
takes place but distinctly slower. The first sign of repair in Lymnaea stagnalis was 
often visible three days after removal of the shell -fragment. It was a thin proteinaceous 
layer which already contained calcium carbonate crystals. In many cases however, 
the regeneration membrane 2 appeared later. 

Histology and histochemistry of the mantle underlying the damaged shell area. 

The results are represented in Table 1. The shell defect was situated near or above 
the kidney; the underlying mantle epithelium was compared with equivalent epithelium 



"The membrane formed in the damaged area of the shell. 



56 



PROC. FOURTH EUROP. MALAC. CONGR. 





* m 




В 

FIG. 3. Size of cells and activity of alkaline phosphatase in the mantle epithelium, 12 days after 
shell injury. A, Exposed mantle epithelium; intense activity of alkaline phosphatase in the api- 
cal parts of the cells; cell height 24-30 д. Note that also the nuclei are enlarged considerably. 
B, Equivalent mantle area of control snail; no activity of alkaline phosphatase; cell height 6-8 ц 
(azo dye method, freeze-dried sections, x700). 



of control snails. In all investigated snails the epithelium of the mantle border showed 
an intense reaction of alkaline phosphatase and RNA which indicates that the snails 
were actively secreting shell material at the time of fixation (Timmermans, 1969). 
Within 24 hours after damage of the shell, no enlargement of the cells was observed. 
The amount of alkaline phosphatase and RNA was small and did not differ from the 
controls. 

Three days after damage to the shell, the mantle epithelium had enlarged from the 
mantle edge up to and including the damaged area. The cell length was 8-12 ц, whereas 
in control snails the cell length was 6-8 ¡л. The amount of RNA had increased consider- 
ably in the whole epithelium, whereas the activity of alkaline phosphatase was weak, 
even less than in control snails. 

Five days after damage of the shell the epithelium was considerably thickened over 
its whole length from the mantle edge up to and including the damaged area. The cell 
length was 15-18 ц, an increase of more than 50% compared with control snails. The 



TIMMERMANS 57 

amount of RNA had increased considerably in the whole slice and the activity of alka- 
line phosphatase had increased too. 

Seven and eight days after damage of the shell the epithelium was thickened up to 
24-30 ц, the cells were three or four times as large as in control snails. In this group 
the area of cell enlargement and increased activity was restricted to the epithelium 
underlying the damaged shell area. This epithelium contained a large amount of RNA 
and a distinct activity of alkaline phosphatase. 

Twelve, fifteen, sixteen days after damage of the shell. The area of cell elongation 
and activity was restricted to the epithelium underlying the damaged shell area. In 
this area the length of the cells was 24-30 ц (Fig. ЗА), i.e., three or four times as 
large as in the epithelium of control snails (Fig. 3B). The thickened epithelium showed 
intense reactions for RNA and alkaline phosphatase (Fig. ЗА). 

Twelve and sixteen days after damage of the shell a group of snails was fixed in 
formol calcium and the peroxidase reaction was carried out. The exposed epithelium 
showed an intense reaction, whereas the mantle epithelium of control snails remained 
unstained. A positive reaction was also obtained in the regeneration membrane. 

Twenty-one days after damage of the shell, cell elongation was restricted to the 
exposed area of the mantle. The epithelium showed less activity, compared to 12 and 16 
days after damage. The length of the cells was 20-30 ц, the amount of RNA and alkaline 
phosphatase had decreased, but was still considerable. 

In many cases, the mantle epithelium underlying the damaged shell area was injured 
and appeared to have vanished. In these cases the "wound" area was filled up with a 
large number of cells. These might be amoebocytes carrying repair material to the 
damaged shell. However, alkaline phosphatase and RNA have never been detected in 
these cells, whereas the epithelium surrounding the wound was thickened and contained 
large amounts of RNA and alkaline phosphatase. 

DISCUSSION 

The mantle 

After damage to the shell at some distance from the mantle border, an increased 
activity is noticed in the outer mantle epithelium resulting in an enlargement of the 
cells and an increasing content of RNA and alkaline phosphatase. At first, the whole 
epithelium from the mantle border up to and including the repair area is activated. 
Clearly, the stimulated portion of the mantle is considerably larger than the area in 
contact with the shell defect. Afterwards, beginning 8 days after shell damage, the 
area of activated epithelium becomes restricted to the region underlying the damaged 
shell area. The signs of increased activity were not observed before three days after 
shell damage and at that time a regeneration membrane containing calcium salts is 
mostly present already. This indicates that the repair processes had started earlier 
though they could not be detected with the applied methods. Abolins-Krogis (1963) 
observed in Helix changes in the mantle tissue related to shell repair within three 
hours after shell damage. However, she did not observe RNA, alkaline phosphatase 
and cell elongation in the mantle epithelium. According to her, (1963, 1968) the mantle 
and the digestive gland in Helix are activated after damage of the shell and repair 
material and calcium are transported by amoebocytes from these regions towards the 
damaged part of the shell. Also Wagge (1951), Wagge & Mittler (1953) and Kapur & 
Gupta (1970) report amoebocytes to be involved in shell repair in land snails. The 
results obtained in the present study, and also those of Durning (1957) for Helix and 
of Beedham (1965) and Saleuddin (1967, 1969) for Anodonta, indicate clearly that the 
mantle epithelium plays an important role in shell repair. The increase in RNA indi- 
cates that proteins are synthesized which are necessary for the matrix of the re- 



58 PROC. FOURTH EUROP. MALAC. CONGR. 

generation membrane; the increase in alkaline phosphatase may be connected with 
calcium deposition and the appearance of peroxidase indicates that the secreted 
proteins are tanned. A fair amount of RNA and alkaline phosphatase in the epithelial 
cells of the mantle after damage of the shell, is reported by Durning (1957) for Helix 
and by Saleuddin (1967) for Anodonta. Saleuddin (1969) found a twofold increase in 
activity of alkaline phosphatase. 

The increase in RNA and alkaline phosphatase and the appearance of peroxidase in 
the exposed epithelium proves that this epithelium is capable of transformation and of 
obtaining functions normally restricted to specific cell groups of the mantle border. 
Moreover, RNA and peroxidase, on the one hand, and alkaline phosphatase, on the 
other hand, which in the mantle edge are contained in separate cell groups, are located 
in the same cells in the repair area. Beedham (1965) observed in Anodonta too that 
different shell -forming functions are performed by one and the same type of cells in 
the repair area. First the cells become elongated and form a periostracum and 
prismatic layer. At that time they resemble histologically and histo chemically the 
cells in the periostracum-forming region. Afterwards, these cells resume their 
normal shape while repairing the inner calcareous layer. The same phenomenon 
was described with electron microscopy by Kawaguti and Dcemoto (1962) for the bi- 
valve Musculus. Taylor and Kennedy (1969) showed in Anodonta that periostracum 
and prismatic sheets can also be formed spontaneously in the nacreous layer of un- 
damaged shells. Beedham concluded from his observations that the relationship which 
normally exists between the different shell layers and the secretory epithelial zones 
of the mantle are not specific and unalterable. The present study shows that this is 
also true for a representative of the gastropods. The possibility of the underlying 
epithelium being destroyed after damage to the shell in Lymnaea stagnalis, so that 
cell elongation and the appearance of peroxidase would be properties of new cells and 
not newly acquired properties of existing cells, must be rejected. Shortly after damage 
a large area of epithelium reacts with elongation and with the appearance of new com- 
pounds, whereas the "activation" is only afterwards restricted to the epithelium under- 
lying the damaged area. 

According to Beedham, in Anodonta the periostracum is repaired after damage to 
the shell. In Lymnaea stagnalis the presence of peroxidase in the exposed epithelium 
suggests that in this snail also the periostracum is repaired. However, histological 
and histochemical investigations indicate that in the regeneration membrane two types 
of lamellae are formed; one type is histologically and histochemically similar to the 
matrix of the calcareous layers, the other may have the same properties as the 
periostracum (to be published). These results suggest that periostracum material is 
actually formed, but probably not a true periostracum. 

Source of calcium 

The calcium necessary for shell repair has been supposed to be provided by the 
neighbouring areas in the shell (Wagge, 1951), by calcium cells of the digestive gland 
(Wagge, 1951; Abolins-Krogis, 1961, 1968), by calcium cells situated in the connective 
tissue of the mantle (Durning, 1957; Guardabassi and Piacenza, 1958; Tsujii, 1960; 
Abolins-Krogis, 1963) and by the food (Wagge, 1951; Bierbauer, 1957). Wagge 
(1951) observed in Helix that calcium is not deposited in the shell when food 
is lacking. Bierbauer (1957) observed in histochemical and quantitative inves- 
tigations in Helix that the amount of calcium in the digestive gland and mantle 
is not diminished during shell regeneration and that in springtime and summer 
when feeding conditions are good, regeneration is accomplished in much shorter 
time than in winter. Shell repair was accelerated by injections of calcium. Bier- 
bauer (1957) concluded from these observations that in Helix the calcium, neces- 



TIMMERMANS 59 

sary for shell repair is derived from the food and not supplied by the calcium 
cells of the mantle and digestive gland. In Lymnaea stagnalis it has been shown in 
experiments with calcium-45 added to the water that calcium is rapidly deposited in 
the shell, particularly in the shell edge, whereas in the calcium cells of mantle and 
digestive gland only a limited amount is deposited (Timmermans, 1969). This indi- 
cates that in this animal under normal circumstances the calcium cells do not provide 
the calcium for the shell of fast growing snails; it may be assumed that also for shell 
repair, the necessary calcium is supplied by the surrounding water or by the food. 
According to Van Der Borght and Van Puymbroeck (1966) nearly all the calcium ob- 
tainable from the food is extracted by Lymnaea stagnalis but nevertheless about 80% 
of the acquired calcium is derived directly from the water. This calcium is taken up 
against an electrochemical potential gradient (Van Der Borght & Van Puymbroeck, 
1964). 

Calcium transport 

Wagge (1951), Wagge and Mittler (1953) and Abolins-Krogis (1963, 1968) supposed 
that in Helix calcium and other repair material is transported by amoebocytes, which 
migrate into the exposed surface of the mantle and which secrete and calcify the 
repair membrane. In Lymnaea stagnalis such transport was not observed. In the area 
underlying the damaged shell region in this animal, a large accumulation of small cells 
is observed only when the epithelium is damaged too. However, positive reactions 
were not obtained in these cells with the applied histochemical methods. The fact 
that these cells are observed only in areas of damaged epithelium and not below the 
surrounding activated epithelium or in an exposed mantle area with intact epithelium 
suggests that these cells have a protective function against inflammation. The manner 
in which calcium and other repair material is transported to the exposed epithelium 
in Lymnaea stagnalis still remains to be solved. 

ACKNOWLEDGEMENTS 

I wish to thank Prof, Dr. Chr. P. Raven for his valuable criticism and critical 
reading of the manuscript; Mrs. J. Akkermans-Kruyswijk for careful technical assis- 
tance and Mr. H„ van Kooten and co-workers for preparing the photographs. 

LITERATURE CITED 

ABOLINS-KROGIS, A., 1961, The histochemistry of the hepatopancreas of Helix 

pomatia (L.) in relation to the regeneration of the shell. Ark. Zool., 13: 159-202. 
ABOLINS-KROGIS, A., 1963, The histochemistry of the mantle of Helix pomatia (L.) 

in relation to the repair of the damaged shell. Ark. Zool., 15: 461-474. 
ABOLINS-KROGIS, A., 1968, Shell regeneration in Helixpomatia with special reference 

to the elementary calcifying particles. Symp. zool. Soc. Lond., 22: 75-92. 
BEEDHAM, G. E., 1965, Repair of the shell in species of Anodonta. Proc zool. Soc. 

Lond., 145: 107-125. 
BIERBAUER, J., 1957, Untersuchungen über die Regeneration und Histologie von 

Helix pomatia. Acta biol. Acad. Sei. hung., 7: 419-431. 
BRÄCHET, J., 1953, The use of basic dyes and ribonuclease for the cytochemical 

detection of ribonucleic acid. Quart. J. microsc. Sei., 94: 1-10. 
VAN DER BORGHT, O. & VAN PUYMBROECK, S., 1964, Active transport of alkaline 

earth ions as physiological base of the accumulation of some radionuclides in 

freshwater molluscs. Nature, Lond., 204: 533, 534. 
VAN DER BORGHT, O. & VAN PUYMBROECK, S., 1966, Calcium metabolism in a 



60 PROC. FOURTH EUROP. MALAC. CONGR. 

freshwater mollusc: quantitative importance of water and food as supply for cal- 
cium during growth. Nature, Lond., 210: 791-793. 
DURNING, W. C, 1957, Repair of a defect in the shell of the snail Helix aspersa. J. 

Bone Jt Surg., 39A: 377-393. 
DUYN, P. van, 1955, An improved histochemical benzidine-blue peroxidase method 

and a note on the composition of the blue reaction product. Reel. Trav. chim. 

Pays-Bas Belg., 74: 771-778. 
GUARDABASSI, A. & PIACENZA, M. L., 1958, Le manteau de l'escargot Helix pomatia. 

Etude cytologique et ni sto chimique. Arch. Anat. microsc. Morphol. exp., 47: 25-46. 
JOOSSE, J. & LEVER, J., 1959, Techniques of narcotization and operation for experi- 
ments with Lymnaea stagnalis (Gastropoda Pulmonata). Proc. K. ned. akad. 

Wetensch. (C), 62: 145-149. 
KAPUR, S. P. & SEN GUPTA, A., 1970, The role of amoebocytes in the regeneration 

of shell in the landpulmonate, £M/>/ec£a¿nd¿ca (Pfeiffer). Biol. Bull., 139: 502-509. 
KAWAGUTI, S. & ЖЕМОТО, N., 1962, Electron microscopy on the mantle of a bivalve, 

Musculus senhousia during regeneration of the shell. Biol. J. Okayama Univ., 

8: 31-42. 
KESSEL, E., 1933, Über die Schale von Viviparus viviparus L. und Viviparus fasciatus 

MU11. Ein Beitrag zum Structurproblem der Gastropodenschale. Z. Morphol. Ökol. 

Tiere, 27: 129-198. 
PEARSE, A. G. E., 1960, Histochemistry, theoretical and applied. 2nd. ed., Churchil, 

London, 998 p. 
PEARSE, A. G. E., 1968, Histochemistry, theoretical and applied. 3rd ed., Churchil, 

London, 759 p. 
SALEUDDIN, A. S. M., 1967, The histochemistry of the mantle during the early stage 

of shell repair. Proc. malacol. Soc. Lond., 37: 371-380. 
SALEUDDIN, A. S. M., 1969, Isoenzymes of alkaline phosphatase in Anodonta grandis 

(Bivalvia: Unionidae) during shell regeneration. Malacologia, 9: 501-508. 
SIMROTH, H. & HOFFMANN, H., 1908-1928, Mollusca, Gastropoda, Pulmonata. In: 

H. G. Bronn, ed., Klassen und Ordnungen des Tier-Reichs. 3 2(2): 178-205. 

Akademische Verlagsgesellschaft, Leipzig, 1354 p. 
TAYLOR, J. D. & KENNEDY, W. J., 1969, The influence of the periostracum on the 

shell structure of bivalve molluscs. Cale. Tiss. Res., 3: 274-283. 
TIMMERMANS, L. P. M., 1969, Studies on shell formation in molluscs. Neth J. Zool., 

19: 417-523. 
TSUJII, T., 1960, Studies on the mechanism of shell- and pearl-formation in Mollusca. 

J. Fac. Fish. pref. Univ. Mie-Tsu, 5: 2-70. 
WAGGE, L. E., 1951, Amoebocytic activity and alkaline phosphatases during the 

regeneration of the shell in the snail Helix aspersa. Quart. J. microsc. Sei., 92: 

307-321. 
WAGGE, L. E. & MITTLER, T., 1953, Shell regeneration in some British molluscs. 

Nature, Lond., 171: 528-529. 
WILBUR, K. M., 19 64, Shell formation and regeneration. In: WILBUR, K. M., & YONGE, 

C. M., Physiology of Mollusca, I: 242-282. Academic Press, New York, 473 p. 



TIMMERMANS 61 

RESUME 

ACTIVITE DU MANTEAU PENDANT REGENERATION DE LA COQUILLE 
CHEZ L'ESCARGOT LYMNAEA STAGNALIS L. 

Lucy P. M. Timmermans 

Des études histologiques et histochimiques ont été appliquées au manteau de Lymnaea 
stagnalis à intervalles divers après ablation d'un fragment de coquille. 

Dans la région du manteau, située au-dessous delà fracture de la coquille, l'épithe- 
lium s'est épaissi montrant une augmentation d'ARN et de phosphatase alcaline. Au 
début ( 3 à 5 jours après la fracture), la région activée était considérablement plus 
étendue que Г epithelium au-dessous de la fracture. Plus tard (16-18 jours) l'activité 
s'est limitée à la région découverte. L'enzyme peroxidase a été détectée dans l'épi - 
thelium découvert et dans la fraction régénérée de la coquille. 

Ces résultats ont montrés l'importance de l'épithelium du manteau pour la régéné- 
ration de la coquille. L'apparition de peroxidase dans l'épithelium découvert et dans 
la fraction régénérée de la coquille, a indiquée que des protéines tannées ont été 
formées après fracture de la coquille. 



MALACOLOGIA, 1973, 14: 63-79 

PROC. FOURTH EUROP. MALAC. CONGR. 

A NEW THEORY OF FEEDING AND DIGESTION IN THE FILTER-FEEDING 

LAME LLIBRANCHIA 

Brian Morton 

Department of Zoology, The University of Hong Kong 

ABSTRACT 

Recent observations regarding the feeding and digestive processes of the filter- 
feeding Lamellibranchia do not find accord with the currently accepted concept 
of continuous and simultaneous feeding and digestion in these animals. 

A new theory embracing both the old and the new facts is put forward in which 
these processes are considered to be rhythmic in nature. 

INTRODUCTION 

Amongst the Bivalvia, the Lamellibranchia form a relatively homogenous grouping 
that most taxonomists agree are distinct from the Protobranchia, e.g., Ridewood 
(1903), Pelseneer (1911), J. E. Morton (1967), Owen (1959), Purchon (1959), Yonge 
(1959). The Septibranchia are linked by some with the Lamellibranchia, e.g., Newell 
(1965), J. E. Morton (1967), but not by others, e.g., Pelseneer (1911), Purchon (1960, 
1962). 

In the primitive Protobranchia the digestion of food is considered to be mainly extra- 
cellular (Owen, 1956), whilst there isapaucityof information on the feeding and diges- 
tive processes of the scavenging Septibranchia (Yonge, 1928). 

The Lamellibranchia (constituting the majority of the Bivalvia) exhibit a wide 
variety of form and exploit a wide range of aquatic environments. They do, however, 
possess many common features not the least of which is that they are mostly filter- 
feeders and that the process of digestion is both extra-cellular and intra-cellular. 

The processes of feeding and digestion in the Lamellibranchia are considered to be 
continuous and simultaneous. Owen (1966) states that "the more or less continuous 
mode of feeding which characterises the majority of bivalves would seem to preclude 
a synchronous activity of the digestive system." Purchon (1968) can also be quoted 
as reporting that "It is generally considered that feeding and digestion are continuous 
processes in bivalves, new food material being added all the time, and unwanted 
material being as constantly eliminated by passage into the mid gut." Purchon (1971) 
has, however, subsequently suggested, in the light of new evidence, that these processes 
may not be continuous and that a reappraisal of current thought on this subject is 
called for. 

Owen (1955) showed how such a continuous system could operate, and there can be 
little doubt that the components of the feeding and digestive processes he elucidated 
do operate in the Lamellibranchia. This is not questioned. The purpose of this paper 
is to demonstrate that these component processes do not necessarily occur simulta- 
neously and continuously and to show that feeding and digestion in the Lamellibranchia 
is a dynamic process. 

THE PRESENT THEORY 

It is generally assumed that members of the Lamellibranchia are filtering sus- 
pended or deposited material from the water continually, this process being the 
function of the ctenidia. 

(63) 



64 PROC. FOURTH EUROP. MALAC. CONGR. 

GS 



WF 




FIG. 1. A diagrammatic representation of the suggested functioning of the stomach and digestive 
diverticula of the Eulamellibranchia, CS, Crystalline style; DD, Digestive diverticula; FS, Frag- 
mentation spherules; GS, Gastric shield; LC, Left caecum; MG, Mid gut; MT, Major typhlosole; 
O, Oesophagus; RC, Right caecum; SS, Style sac; UF, Large unwanted particles; WF, small 
food particles. (After Owen, 1955.) 

As the water is passed through the ctenidia exchange of oxygen and carbon dioxide 
takes place and particulate material is abstracted and passed either up or down the 
gill lamellae to be concentrated in mucoid strings and passed anteriorly. Large par- 
ticles are removed by ciliary sorting mechanisms on the ctenidia and also by powerful 
ciliary tracts on the mantle and visceral mass and passed posteriorly to be ejected as 
pseudofaeces via the inhalant opening. From the ctenidia particles are passed to the 
labial palps where further rigorous sorting takes place. Finally, particles of a suitable 
size are passed to the mouth where they are ingested (Atkins, 1936, 1937a, b, 1938). 

In the stomach the mucoid food string becomes wound around the crystalline style 
(Fig. 1, CS) which acts as a capstan, winding in the string. The tip of the style revolves 
against the gastric shield (GS) and it is assumed that this action mechanically breaks up 
the food material; the style dissolves as it rotates, releasing extra -cellular enzymes 
bound up in its matrix. Since the style is continually dissolving distally it must be con- 
tinually secreted at its basal end. As the food is broken up it is subjected to further 
sorting in the stomach and large indigestible particles are passed to the mid gut (MG) 
in the intestinal groove of the major typhlosole (MT). Small particles are continually 
being passed to the digestive diverticula (DD) where they are phagocytosed, subjected 
to intra-cellular digestive processes and finally assimilated. Waste from the divertic- 
ula is passed back to the stomach in fragmentation spherules (FS) which probably break 
up and aid in the primary extra -cellular digestion of newly arriving food material by 
release of small quantities of enzymes derived from the digestive diverticula. 



MORTON 



65 



TABLE 1. A summary of the species of lamellibranchs in which rhythmicity has been detected. 
The environmental variables to which the rhythms have been correlated have also 
been indicated with the authority. 



Species 



Rhythms detected 



Authority 



A. Freshwater 

Anodonta cygnea 
Anodonta cygnea 
Unió pictorum 
Hyridella australis 
Dreissena polymorpha 

B. Marine 

Venus mercenaria 

Venus mercenaria 

Venus mercenaria 

Crassostrea virginica 

Crassostrea virginica 

Crassostrea virginica 

Crassostrea virginica 

Crassostrea virginica 

Crassostrea virginica 

Ostrea edulis 

Cardium edule 

Cerastoderma (=Cardium) edule 

Árctica islándica 

Mytilus edulis 

Mytilus edulis 

Mytilus califomianus 

Modiolus modiolus 

Modiolus demissus 

Macoma balthica 

Macoma balthica 

Donax semignosus 

Donax denticulatus 

Scrobicularia plana 

Mya arenaria 

Lasaea rubra 

Lasaea rubra 

Teredo navalis 

Pectén jacobaeus 

Lithophaga lithophaga 



Endogenous 




Barnes, 1952, 1955 


Daily 




Sálanki, 1964; Sálanki & Vero, 1969 


Daily 




В. S. Morton, 1970b 


Daily 




Hiscock, 1950 


Daily 




B. S. Morton, 1969b 


Daily 




Thompson, 1970 


Daily 




Bennett, 1964 


Daily, monthly, 27 


-day 


Brown et al., 1956 


Tidal, daily, monthly, 


2 7- day 


Brown, 1954; Brown etal., 1956 


Tidal 




Haskin, 1964 


Tidal 




Carriker, 1951 


Tidal 




Kunkle, 1957 


Tidal 




Nelson, 1918, 1920, 1925, 1933 


Tidal, daily 




Loosanoff & Nomejko, 1946 


Tidal, daily 




B. S. Morton, 1971 


Tidal 




B. S. Morton, 1970a 


) edule Tidal 




Farrow, 1972 


2 x Daily (Tidal 


?) 


Winter, 1969, 1970 


Tidal 




Gompel, 1937 


Tidal 




Rao, 1954 


Tidal 




Rao, 1953 


2x Daily (Tidal 


?) 


Winter, 1969, 1970 


Tidal 




Nagabhushanam, 1963 


Tidal 




B. S. Morton, 1970c 


Tidal 




Thorpe, 1972 


Tidal 




Mori, 1938, 1950 


Tidal 




Trueman, 1971 


Tidal 




Thorpe, 1972 


Tidal, daily, mor 


thly 


Dicks (pers. comm.) 


Tidal 




J. E. Morton, 1956 


Tidal 




McQuiston, 1969 


Daily 




B. S. Morton & McQuiston, 1973 


Daily 




Sálanki, 1966 


Daily 




Sálanki, 1966 



RHYTHMICITY IN THE LAMELLIBRANCHIA 



Occurrence 



Examination of the literature reveals that many lamellibranchs possess rhythms of 
activity (Table 1). 

Pavlov (1885) first noted that the spontaneous activity of the adductor muscles of 
Anodonta assumed a regular periodicity. Marceau (1906, 1909) later showed that very 
many lamellibranchs of widely differing structure and mode of life exhibited a rhythmi- 



66 PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 2. A kymograph record of the activity of Dreissena polymorpha. 

cal activity of the adductors. Subsequent research has shown that in most cases the 
rhythms so described can be correlated in some adaptive fashion with the rhythm 
of the environment. Anodonta apparently possesses an endogenous rhythm (Barnes, 
1952, 1955) although recently Sálanki (1964) and Sálanki & Vero (1969) have suggested 
that this species may also possess a rhythm related to the phases of night and day. 

Littoral lamellibranchs are affected by the rhythm of the tide and can be expected to 
respond to such environmental extremes. What is of interest, however, is that fresh 
water and sub-littoral forms also possess rhythms of activity and inactivity related to 
another environmental variant - night and day. 

Monthly or semi-lunar cycles of activity are produced by the summation of tidal 
and diurnal rhythms in littoral bivalves, and may play an important role in the timing 
of breeding in these genera, as will be discussed later. 

Nature 

The rhythmical nature of lamellibranch behaviour has been recorded in various 
ways, e.g., by measuring the variation in water propulsion (siphoning) (Hopkins, 
1936; Rao, 1953, 1954) or oxygen consumption (Gompel, 1937) but by far the most 
revealing method is to record the shell valve movements directly by means of a kymo- 
graph (Barnes, 1955; Koshtoyants & Sálanki, 1957). In every case which has been 
studied it has been shown that the period of activity is characterised by rapid phasic 
contractions, whilst the period of rest is characterised by either closure or gaping of 
the shell valves (Fig. 2) according to the species (Marceau, 1906, 1909). The phasic 
contractions rapidly close the shell valves, but relaxation of the adductor muscles 
allows the elastic ligament to force the shell valves open. This process is repeated 
many times during the period of activity. The "quick" portion of the adductor muscles 
might be responsible for phasic adductions whilst the "catch" portion of the adductor 
muscles might be responsible for the maintained closure of the shell valves during the 
quiescent period. In those lamellibranchs which gape during their quiescent period 
it would seem the "catch" mechanism is only used when the animal is disturbed. 



MORTON 67 

Effect 

The phasic contractions characteristic of the period of activity serve as a pump. 
Rapid closure of the shell valves forces filtered water (lacking in oxygen but rich in 
carbon dioxide) out of both inhalant and exhalant apertures and pseudof aeces and faeces 
out of the inhalant and exhalant apertures respectively. Opening of the valves again, 
reduces the pressure in the mantle cavity relative to the outside and fresh water 
enters via the inhalant aperture. Salanki & Lukacsovics (1967) have shown that 
Anodonta is rapidly filtering at this time and that oxygen consumption is also high. 

During the period of quiescence the shell valves either close or gape according to the 
genus (Marceau, 1906, 1909). Whichever action is utilised the effect is the same, the 
water in the mantle cavity is not replenished by muscular action and filtration all but 
ceases. Salanki & Lukacsovics (1967) have shown for Anodonta that filtration is mini- 
mal and oxygen consumption negligible at this time. It has also been shown for Dreis- 
sena that filtration ceases at this time (B. S. Morton, 1970e) and in Cardiiim edule and 
Teredo navalis (B. S. Morton, 1970a; B. S. Morton & McQuiston, 1973) that the pH of 
the fluid in the mantle cavity falls, indicating that it is being depleted of oxygen and 
greatly enriched with carbon dioxide. Koch &Hers (1943) reported a similar rhythmi- 
city in siphonal activity and oxygen uptake in Anodonta and Galtsoff (1964) and Salanki 
& Lukacsovics (1967) have recommended that shell valve activity be taken into account 
when studying filtration in lamellibranchs. 

The regularity of these alternating processes of adduction and of quiescence in so 
many lamellibranchs precludes artefacts and to the contrary suggests that it is ex- 
tremely important and is an intrinsic lamellibranch character. 

FILTER FEEDING 

It has been shown in many bivalve genera that the rhythmical nature of the adduction 
of the shell valves has a profound effect upon feeding. The phasic adductions charac- 
teristic of the period of activity greatly enhance the food trapping mechanisms by 
constantly replenishing the water in the mantle cavity. It has been considered that 
the ctenidia themselves were solely responsible for the inhalant stream; it now seems 
likely that this action is supplemented by the pumping motion of the shell valves. 
The long periods of quiescence observed in lamellibranchs limit feeding while the 
shell valves are shut or gaping. It would seem therefore that a high level of filter 
feeding in the Lamellibranchia is not necessarily continuous. 

FUNCTIONING OF THE STOMACH AND DIGESTIVE DIVERTICULA 

Unless such genera possess mechanisms for converting an irregular supply of 
food material into a constant stream then their digestive processes can not be 
continuous and simultaneous. It can be assumed that shortly after the last phasic 
adduction of a period of activity the mantle cavity is comparatively free of particulate 
material and all acceptable material has been passed to the stomach. In rare excep- 
tions food may be stored in special organs associated with the stomach, e.g., the appen- 
dix of the Teredinidae. However, as will be discussed later the appendix generally has 
quite a different function. For most lamellibranchs it must be assumed that the cessa- 
tion of feeding has a profound effect upon the digestive process. 

The stomach contents 

It has been shown for Ostrea edulis (B. S. Morton, 1971) that the constituents of 
the stomach fluids change considerably over the tidal cycle. The same is true for 
the appendix of Teredo navalis (B. S. Morton & McQuiston, 1973). 



68 PROC. FOURTH EUROP. MALAC. CONGR. 

When Ostrea is feeding the stomach is full of ingested material. At the start of 
feeding this is in the form of distinct mucoid food strings. These strings are not pre- 
sent for long and it is not considered that the style is continually winding in food chains 
as previously thought. Later the food disappears from the stomach and for a short 
time the stomach fluid is relatively clear. Still later the stomach begins to fill with 
fragmentation spherules derived from the digestive diverticula; eventually these too 
disappear and food begins to enter the stomach with the recommencement of feeding. 

Diurnal changes were also observed in the appendix of Teredo navalis and these re- 
flected the changes occurring in the much smaller stomach, and showed a close simi- 
larity to the changes observed in the stomach of Ostrea, with the additional complica- 
tion of the presence of wood fragments in the former (B. S. Morton & McQuiston, 1973). 

The crystalline style 

One of the most important single factors that has led to the acceptance of a concept 
of continuous feeding and digestion in the Lamellibranchia was the belief that the slow 
dissolution of the crystalline style released a constant supply of the enzymes that ef- 
fect extra-cellular digestion of food material in the stomach. Constant dissolution 
assumed constant secretion at the basal end (J. E. Morton, 1952). Mitra (1901), how- 
ever, believed the dissolution of the style to be periodic. Nelson (1918, 1920, 1925, 
1933) showed that the style of Ostrea virginica was not always present and that on a 
rising tide it was a large firm rod, but on a falling tide it was reduced to an amor- 
phous gelatinous mass. He further showed that the style of Ostrea could be reformed 
in 15 minutes. J. E. Morton (1956) similarly showed that the style of Lasaea rubra 
was formed and dissolved during every tidal cycle. Owen (1966) has stated that the 
style of lamellibranchs dissolves when the animals are kept out of water, under an- 
aerobic conditions (also noted by Berkeley (1923)) or when the 2 valves are clamped 
together. Under natural conditions littoral animals are out of water at low tide; anaer- 
obic conditions exist in the mantle cavity at certain times (i.e., during the quies- 
cent phase) and very often lamellibranchs clamp their shell valves together for long 
periods of time. 

My own studies on Dreissena polymorpha, Cardium edule and Ostrea edulis (B. S. 
Morton, 1969b, 1970a, 1971) have shown that the style dissolves either just before or 
during the early stages of feeding. This agrees with the findings of J. E. Morton (1956) 
on Lasaea. In O. virginica (Nelson, 1920), O. edulis (B. S. Morton, 1971) and Lasaea 
rubra (J. E. Morton, 1956) the style dissolves completely. This is not so in D. poly- 
morpha and C. edule (B. S. Morton, 1969b, 1970a) in which it only partially dissolves. 
The enzymes of the crystalline styles of numerous lamellibranchs are well documented 
(Owen, 1966; Purchon, 1968) but since the style only dissolves occasionally these en- 
zymes are released only intermittently and consequently extra- cellular digestion in 
the stomach is rhythmic too. The site of secretion of the matrix of the style is now 
generally assumed to be the typhlosole, e.g., List (1902), Nelson (1918), Lazier (1924), 
Graham (1931), Goreau et al. (1966), В. S. Morton (1969a, 1970a,d), Giusti (1970). 
The ciliated cells of the style sac itself probably only serve to rotate the style though 
they may also be responsible for the secretion of some enzymes. 

The laminar nature of the style (Nelson, 1918; Kato & Kubomura, 1954; B. S. Mor- 
ton, 1969a, 1970a) suggests that it is secreted intermittently. It is now postulated that 
at the time of secretion (Fig. 3,A), style material is poured into the style sac and coats 
the surface of the style; this has the effect of pushing the style forward, and this pro- 
cess is aided by the cilia which rotate the style. Eventually the newly produced style 
material solidifies and secretion stops. Dissolution begins (Fig. 3,B) and ceases when 
the thin basal end of the style is no longer in contact with the cilia of the style sac and 
cannot be pushed forward any further. This process in all probability occurs in those 



MORTON 



69 





В 



FIG. 3. A diagrammatic representation of the 2 processes of (A) secretion and (B) dissolution 
of the crystalline style of the Lamellibranchia. 



bivalves in which the style does not dissolve completely, and accounts lor the known 
facts regarding the lengthening and thickening of the style. In those bivalves in which 
the style dissolves completely, e.g., Ostrea and Lasaea, the process is much simpler 
although probably the same principles are involved; the style is secreted at one time 
and dissolved at another. 

One of the commonest misconceptions regarding the crystalline style of lamelli- 
branchs is that it is the most acid organ in the gut (Yonge, 1925, 1926a). In bivalves 
examined subsequently (B. S. Morton, 1969b, 1970a, 1971) the style has been approxi- 
mately neutral, or at the most only slightly acid. The digestive diverticula appear to 
be the most acid region of the gut and in most species (but not in Ostrea edulis), the 
style does not buffer the stomach contents. This is true for Dreissena and Cardium 
where the pH of the stomach fluids varies widely over the course of the diurnal and tidal 
cycle respectively (B. S. Morton, 1969b, 1970a). In O. edulis the pH of the stomach con- 
tents remain fairly stable over the tidal cycle. 

The gastric shield 

The gastric shield of the Lamellibranchia is largely restricted to the left dorsal wall 
of the stomach. It has generally been regarded as protecting the stomach wall from the 
abrasive effect of the rotating crystalline style, though it may (Yonge, 1949) assist in 



70 PROC. FOURTH EUROP. MALAC. CONGR. 

the trituration of stomach contents. Halton & Owen (1968) have shown that the gastric 
shield of the protobranch Nucula sulcata is enzymatically active. They further suggest 
that the gastric shield of lamellibranchs may also be enzymatically active, an obser- 
vation supported by the recent work of McQuiston (1970), and not simply an inert pro- 
tective structure. Should it subsequently be proven that the gastric shield generally 
plays an active role in digestion it is possible that this function would be closely asso- 
ciated with the functioning of the crystalline style and as such similarly regulated. 

The sorting areas of the stomach 

Purchon (1956, 1957, 1958, 1960) has made an especial survey of the stomach in the 
Bivalvia. In the Lamellibranchia the stomach possesses sorting areas that principally 
function by removal to the mid gut of large or indigestible particles leaving a suspen- 
sion of fine particles for primary extra-cellular digestion by enzymes liberated by the 
style and subsequent transmission to the digestive diverticula for intra -cellular 
digestion. 

Since it has been shown that lamellibranchs are not continually feeding, food is not 
always in the stomach and it therefore follows that the sorting areas are not always 
sorting potential food material. This is particularly true for the eulamellibranch sort- 
ing area type С (Reid, 1965b) in the digestive caeca. It is probable that in this organ 
the sorting mechanism manipulates food at one time and waste material at another. 

The appendix 

As noted earlier the contents of the appendix of Teredo navalis vary systematically 
over the course of 24 hours. Wood is always present, but at certain times either frag- 
mentation spherules or filtered material too large to be digested are also found. As in 
Ostrea particulate material other than fragments of wood never occurs simultaneously 
with the fragmentation spherules. It appears that the appendix of Teredo serves partly 
as a temporary store of unusable or unwanted material and perhaps also as a reserve 
of potential food material. Purchon (1960) and Reid (1965b) have suggested the former 
function for the appendix of the Tellinacea which is homologous with the appendix of the 
Teredinidae (Yonge, 1949). Reid (1965b) further suggested that contraction of the ad- 
ductor muscle periodically emptied the appendix of Lima Mans. 

The digestive diverticula 

The digestive diverticula of the Lamellibranchia all possess a striking similarity. 
Their function has been elucidated by Yonge (1926b) and Owen (1955) who subsequently 
(Yonge, 1939; Owen, 1956) also showed that they differ fundamentally from those of the 
Protobranchia. 

The digestive diverticula are organs of absorption and intra-cellular digestion (List, 
1902; Vonk, 1924; Yonge, 1926b; Owen, 1955; Dinamani, 1957; Saleuddin, 1965; Sumner, 
1966a,b; B. S. Morton, 1969a, 1970a,d). Mansour (1946), Mansour & Zaki (1946) and 
Mansour-Bek (1946) also considered them to be organs of secretion. It was considered 
by Owen (19 55) that this secretory function could be derived from the disruption of frag- 
mentation spherules, carrying the waste products of intra-cellular digestion, in the 
stomach. Subsequently Sumner (1966a,b) and McQuiston (1969) attributed a secretory 
function to the basiphil cells or "nests of young cells" of Yonge (1926b) which were 
considered to be responsible for the replacement of old spent digestive cells and 
the formation of new tubules (Yonge, 1926b; J. E. Morton, 1956; B. S. Morton, 
1969b, 1970a,b,c, 1971). 

Owen (1970) has now apparently clarified the issue and shown that the "nests of young 
cells" are composed of two cell types, one of which is secretory, the other perhaps 
being responsible for the replacement of both secretory and absorptive cells. 



MORTON 71 

The location of the digestive diverticula in relation to the stomach varies from species 
to species, but in the Lamellibranchia they are mainly restricted to caeca. In many, 
but not all cases, the openings to the digestive diverticula are associated with an in- 
pushing of the major typhlosole which projects into the duct leading to the diverticula 
(Sorting area type С (Reid, 1965b)). Particles of food enter the caeca where they are 
transported to the openings of the ducts. It was assumed that small particles were con- 
tinually entering the ducts and that the digestive diverticula were continually absorbing 
fluid and phagocytosing small particles. It was necessary to postulate a two way flow 
in the ducts supplying the diverticula in order to explain how the waste products of di- 
gestion could pass out while food material was entering. The counter -current theory 
(Owen, 1955) explained how this system could operate. Undoubtedly the principle under- 
lying this theory is correct. The food entering the ducts does travel in the "upper" part 
of the duct and waste does travel out of the diverticula in the "lower" part of the tube 
(Mathers, 1972). The system, however, is not necessarily a counter-current since food 
is not necessarily entering the diverticula at the same time that waste is leaving the 
diverticula. It has now been established for Dreissena, Cardium, Anodonta, Macoma, and 
Ostrea (B. S. Morton, 1969b, 1970a,b,c, 1971) that the digestive diverticula undergo a 
pattern of cytological changes that is related to the feeding and digestive rhythm. This 
pattern closely approximates to that demonstrated by J. E. Morton (1956) and subse- 
quently confirmed by McQuiston (1969) for Lasaea and the stages can be defined as 
1) Formation, 2) Absorption and phagocytosis, 3) Digestion, 4) Breakdown, 5) Develop- 
ment and Formation (1). To this sequence must now be added the secretory function 
described by Sumner (1966a,b), McQuiston (1969) and Owen (1970). The enzymes are 
probably secreted prior to or during the absorptive phase. 

During breakdown of the diverticula, the absorptive cells disintegrate releasing frag- 
mentation spherules which pass into the stomach. Owen (1955) has suggested that 
their disruption in the stomach may aid primary extra-cellular digestion. This is prob- 
ably true for some genera, e.g., Lasaea rubra (J. E. Morton, 1956), but since they are 
probably more acid than the organ that produces them, they may more importantly, 
also initiate style dissolution. pH may not be solely responsible for dissolution of the 
style at this time since the proteinaceous style (Bailey & Worboys, 1960) would be 
liable to dissolve if a protease were present (Reid, 1965a). Such a protease could be 
found in fragmentation spherules containing excess intra-cellular proteases derived 
from the digestive diverticula (Yonge, 1923; Rosen, 1949; Ganapati & Nagabhushanam, 
1956). 

Movement of food and waste in the stomach 

Ciliary mechanisms have been considered as the main propulsive source for the 
movement of particles in the stomach of lamellibranchs. It has, however, been shown 
that the cilia at the opening of the caeca into the stomach usually beat out of the caeca 
thereby apparently hindering the entry of food material, but also probably more import- 
antly, thereby preventing blockage of the openings (Purchon, 1955). Since the counter- 
current theory explaining the two way passage of material in the ducts of the diver- 
ticula may not necessarily function as originally envisaged since the inhalant and ex- 
halant streams are separated temporally as well as spatially, it is necessary to find 
an alternative mechanism to account for the transport of material between the stomach 
and the digestive diverticula. 

The tubules of the digestive diverticula are surrounded by a meshwork of muscle 
fibres. Owen (1955), Millar (1955) and J. E. Morton (1956) have all suggested that con- 
traction of these muscles would expel waste from the diverticula. The last two authors 
report observing this action in Ostrea larvae and in Lasaea respectively. Reid (1965b) 
has suggested that the appendix of Lima is emptied by the contraction of the adductor 



72 



PROC. FOURTH EUROP. MALAC. CONGR. 
FS д WF 

UF 




FIG. 4. Diagrammatic representations of the stomach in the Lamellibranchia showing how the 
digestive processes can be divided into a number of phases. (For lettering see Fig. 1. ) 

muscles, whilst the appendix of Teredo could be emptied by nothing other than by mus- 
cular activity (Purchon, 1960). 

Possibly rapid phasic adductions of the adductor muscles at the time of feeding 
in lamellibranchs may also serve the subsidiary function of squeezing the products of 
extra-cellular digestion in the stomach into the diverticula, and at other times con- 
tractions of the muscle fibres investing the diverticula may help to pass waste mater- 
ials into the stomach. As originally postulated by Graham (1949), Owen (1953) and 
Purchon (1955) opposing muscular forces acting on a fluid medium may be the princi- 
pal agency for the transference of particulate material from one part of the alimen- 
tary tract to another in the Lamellibranchia. 

DISCUSSION 

Critical analysis of the available information suggests that the currently accepted 
theory of a steady state in feeding and digestion in the Lamellibranchia cannot account 
for many of the changes observed in the feeding and digestive processes and which are 
of a cyclical nature. 

For those species examined the following sequence of events has been determined. 

The animal feeds for a period of time. This action is characterised by rapid phasic 
contractions of the adductor muscles which serve to pump water into and out of the 
mantle cavity, thereby supplementing the inhalant ciliary currents produced by the 



MORTON 

FEEDING 



73 



PSEUDO- 
FAEŒS 




FAECES AFTER 

INTRA-CELLULAR 

DIGESTON 



STYLE 
DISSOLVES 



FRAGMENTATION 
SPHERULES 



BREAKDOWN 
OF D.D. 



EXTRA -CELLULAR 

DIGESTIVE 

CYCLE 



STYLE 
FORMS 




ASSIMILATION 



INTRA-CELLULAR 
DIGESTIVE 
CYCLE 



ABSORPTION 
IN D.D. 



FAECES AFTER 

EXTRA-CELLULAR 

DIGESTION 

FIG. 5. A schematic representation of the rhythmic nature of the feeding process and extra- 
cellular and intracellular digestive mechanisms in the Lamellibranchia. 

ctenidia. The ctenidia also serve to effect the filtration of the water once it is in the 
mantle cavity and to initially sort the food. Material of an acceptable size is passed to 
the labial palps for further rigorous sorting and ultimately selected material is trans- 
ported to the mouth for ingestion. 

The food arrives in the stomach at a time when the style (Fig. 4, CS) has either wholly 
or partly dissolved (Fig. 4, A), e.g.,Ostrea edulis (B.S. Morton, 1971) or the arrival of 
food in the stomach initiates style dissolution (Fig. 4, B), e.g., Dreissena polymorpha 
(B.S. Morton, 1969b). In the former case the dissolution of the style is considered to 
have been caused by the arrival in the stomach of the fragmentation spherules (FS) de- 
rived from the digestive diverticula (DD). In the stomach the enzymes released from 
the dissolving style act upon the food to break it up. The partly digested food is then 
sorted in the stomach, large unwanted particles (UF) are passed to the mid gut (MG) 
in the intestinal groove of the major typhlosole (MT) (Fig. 4, B,C,D) and food material 
of an acceptable size is passed to the digestive diverticula for further extra-cellular 
digestion (Owen, 1970), absorption and phagocytosis, intra- cellular digestion and final 
assimilation. Passage of food material into the diverticula may be assisted by the 
phasic contractions of the adductor muscles that are occurring at this time. 

When the animal ceases to feed (Fig. 4, D) (during the period of adductor quiescence) the 
mouth (O) may shut, remaining waste is passed to the mid gut and remaining food passed 
to the diverticula. The final closing action of the shell valves probably also removes the 
last pseudofaeces from the mantle cavity. The crystalline style now reforms and the 
epithelium of the digestive diverticula commence the process of breakdown (Fig. 4, E) 
eventually passing assimilated products to the rest of the body and producing f ragmen- 



74 PROC. FOURTH EUROP. MALAC. CONGR. 

tation spherules which are ultimately passed to the stomach (Fig. 4, A) probably by con- 
traction of the meshwork of muscle fibres surrounding each digestive tubule. The di- 
gestive diverticula reform in preparation for another cycle whilst the fragmentation 
spherules begin to act upon the now fully formed style causing it to dissolve once again. 

The process varies, as would be reasonably expected in such a diverse assemblage 
of animals, but the essential principle (Fig. 5) is evident in all those examined, and is 
usually regulated by an environmental rhythm. 

It would seem to be generally accepted that the evolution of the Lamellibranchia oc- 
curred in the shallow coastal waters. Such animals would have been subjected to the 
twin environmental rhythms of the tide and night and day. These rhythms ace appar- 
ently retained in modern littoral lamellibranchs (Table 1). Adaptive radiation of the 
Lamellibranchia into the sublittoral zone of the sea and into fresh waters removed the 
effect of the tide. Sublittoral forms now possess diurnal rhythms only. Similarly mod- 
ern fresh water forms also possess diurnal rhythms although Anodonta may have taken 
the process one step further and evolved an endogenous rhythm; feeding as the neces- 
sity arises. Apparently the Lamellibranchia have retained either the primitive feeding 
mechanisms related to the tidal cycle or have transferred their feeding rhythm to the 
subsidiary rhythm of night and day. In littoral lamellibranchs, e.g., Crassostrea vir- 
ginica (Brown et al., 1956), Ostrea edulis (B. S. Morton, 1971) and Mya arenaria (Dr. 
B. Dicks, pers. comm.), it has also been suggested that summation of the tidal and 
daily rhythms produce a third rhythm related to the phases of the moon. Brown et al. 
(1956) have shown this rhythm to be of 14.8 days duration, being thus semi -lunar. 

Spawning and the liberation of larvae in Ostrea edulis occurs at fortnightly intervals 
in relation to the phases of the moon(Korringa, 1947; Knight- Jones, 1952). This con- 
firmed the earlier work of Orton (1926) who showed that in this species young larvae 
are more abundant in the gills of the adult immediately after the full moon whilst ma- 
ture larvae showed peaks of abundance later. A lunar periodicity in spawning has also 
been shown for Chlamys opercularis (Amirthalingham, 1928) and Pectén maximus 
(Mason, 1958). The triggering mechanism for the release of larvae or gametes may 
be synchronised by the semi -lunar rhythm built up by the summation of the tidal and 
diurnal rhythms. Temperature may also play a role in ensuring that the gametes or 
larvae are not liberated in the wrong lunar cycle. Such a mechanism has obvious sur- 
vival values. 

It would appear that rhythmicity in the Lamellibranchia is widespread, regardless 
of the habitat and is important in correlating the various components of the complex 
feeding and digestive cycle. 

SUMMARY 

It has hitherto been believed that in the filter-feeding Lamellibranchia the processes 
of feeding and digestion were both held in a steady state. Careful study of both of these 
processes in a number of genera, both freshwater and marine in relation to the time 
factor, has shown this view to be untenable. These processes comprise a rhythmic se- 
quence of phases related to environmental rhythms. Two alternate phases can be de- 
tected. In the first food is collected, filtered, selected and passed to the stomach. 
Food collection then ceases and the accumulated food material is digested. The com- 
plex organs of feeding and digestion in the Lamellibranchia are co-ordinated to a fine 
degree and the processes they initiate achieve a refinement hitherto unsuspected. 
Feeding and digestion in the Lamellibranchia is a dynamic process both temporally 
and spatially. 



MORTON 75 

ACKNOWLEDGEMENTS 

I would like to thank Professor G. Owen, Professor R. D. Purchon and Sir Maurice 
Yonge F. R. S. for their constructive criticism of the first draft of the manuscript of 
this paper. 

Much of my own research embodied in this paper was undertaken when I was a re- 
search student with Professor Purchon and subsequently asa research associate at the 
Marine Laboratory of Portsmouth Polytechnic. 

I have benefited greatly from discussions with many people, but I would particularly 
like to thank Dr. Peter Russell and Dr. Rob McQuiston. 

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78 PROC. FOURTH EUROP. MALAC. CONGR. 

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MORTON 79 

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MALACOLOGIA, 1973, 14: 81-88 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE INFLUENCE OF TEMPERATURE ON THE GROWTH RATE OF 

BULINUS (BULINUS) TROPICUS (KRAUSS) AND LYMNAEA NATALENSIS 

KRAUSS (MOLLUSCA: BASOMMATOPHORA) 

J. F. Prinsloo and J. A. van Eeden 

Snail Research Group of the Medical Research Council 
Potchefstroom University for С H. E., Potchefstroom, South Africa 

It is no unusual experience for the freshwater malacologist who goes collecting 
snails, to end up with a wide range of sizes of the same species taken from the same 
pool at the same time, and it has almost become customary to regard such specimens 
as representing generations of different ages. A series of small specimens from a 
particular area is, furthermore, often identified as dwarfed representatives of a 
normally larger species and their small size is then vaguely attributed to possibly 
suboptimal conditions under which they might have lived. However logical these 
claims may be, their validity has, in our opinion, not yet been tested carefully enough. 

The data discussed in this paper were collected during a laboratory investigation of 
the influence of temperature on such aspects as survivorship, reproduction rate and 
capacity for increase in Bulinus (Bulinus) tropicus (Krauss) and Lymnaea natalensis 
Krauss which was reported on by Prinsloo & Van Eeden (1969). The experimental 
set-up was, therefore, the same as that described in the report cited above. Growth 
rate was measured in terms of increase in mass and for this purpose all the snails in 
the experimental populations were weighed at monthly intervals commencing at 1.5 
months from date of hatching. Thirty to thirty -five specimens of each species were 
reared from egg masses of the same age at each of the selected temperatures. 

GROWTH RATE 

The average mass per specimen at successive ages and at the different temperatures 
tested are given in Table 1 and the growth curves based on these data are reproduced 
in Figs. 1 and 2. 

The data in the table and figures given reveal certain interesting differences be- 
tween the 2 species. Throughout the experiment Bulinus tropicus enjoyed a mass 
advantage over Lymnaea natalensis at 27°, 25° and21°C but at 18° and 15°C the latter 
species grew faster than the former right from the beginning (Table 1). In B. tropicus 
(Fig. 1) the mass increase at 18° and 15°C remained almost negligible up to 1.5 
months and at 15°C this trend was maintained up to 2.5 months. It is, further- 
more, evident that the rate of average mass increase per specimen increased with 
rising temperature and was best at 27°C. At both 27° and 25°C all the snails had died 
out before 4.5 and 5.5 months respectively. Egg deposition at these 2 temperatures, 
as also at 21°C, started almost simultaneously. This occurred before 1.5 months from 
the time of hatching and seems, at all the temperatures tested, to have been linked 
with an average mass of 0.02-0.04 g per specimen which, at 18° and 15°C, was 
respectively reached 1 and 2 months later than at the other temperatures. The best 
average mass increase (0.06-0.08 g per specimen per month) was also recorded at 
27°, 25° and 21°C during the period between 1.5 and 2.5 months. 

In Lymnaea natalensis (Fig. 2), as in Bulinus tropicus, the average monthly rate 
of mass increase at 15°C remained negligible up to 2.5 months after hatching but 



(81) 



82 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLE 1. Monthly average mass in grams per specimen of Lymnaea natalensis and 
Bulinus tropicus reared at constant temperatures. 



Age 


in 

ths 


Species 






Temperature in 


°C 




mon 




27 


25 


21 


18 


15 


1.5 




L. 


natalensis 


0. 


0182 


0.0253 


0.0169 


0.0203 






B. 


tropicus 


0. 


0441 


0.0455 


0. 0243 


0.0051 


- 


2.5 




L. 


natalensis 


0. 


0321 


0. 0405 


0. 0452 


0.0598 


- 




B. 


tropicus 


0. 


1198 


0.1286 


0.0935 


0.0421 


- 


3.5 




L. 


natalensis 




- 


0.0656 


0.0758 


0.1269 


0.0569 




B. 


tropicus 


0. 


1782 


0.1572 


0.1452 


0.0912 


0. 0423 


4.5 




L. 


natalensis 




- 


0.0906 


0.1401 


0.1902 


0.1203 




B. 


tropicus 




- 


0.1980 


0.1748 


0.1298 


0.0822 


5.5 




L. 


natalensis 




- 


- 


0.1803 


0. 2262 


0.1953 




B. 


tropicus 




- 


- 


0.2170 


0.1734 


0.1272 


6.5 




L. 


natalensis 




- 


- 


0.1682 


0.2475 


0. 2534 




B. 


tropicus 




- 


- 


0.2455 


0.2260 


0.1780 



from this age onwards it rose more steeply at this than at any of the other tempera- 
tures. In fact, the general trend was for the rate of mass increase to improve with 
decreasing temperature which is exactly the opposite of what we experienced in the 
case of B. tropicus. All the specimens at 27° С died out before reaching an age of 
3.5 months. This is 1 month sooner than it had occurred in B. tropicus which, there- 
fore, survived both 27° and 25°C better. The best average rate of mass increase 
(0.07 g per specimen per month) was recorded at 18°C during the period between 
2.5 and 3.5 months, i.e., both later and at a lower temperature than in B. tropicus. 

MASS DISTRIBUTION 



In spite of the fact that all the experimental snails were hatched from egg masses 
deposited during the same 24 hour period the mass varied from specimen to specimen 
from the moment of hatching. That this would be so could already be detected in many 
egg masses before hatching. The snails could consequently be arranged in a series 
of mass groups of 12 mgm intervals as was done in Figs. 3-8. At 1.5 months (Fig. 3 
and Table 2) the phenomenon of mass distribution was more marked for Bulinus 
tropicus than for Lymnaea natalensis and the percentage egg masses revealing it was 
distinctly highest at 27° and 25°C. At this age B. tropicus was differentiated into 
larger numbers of mass groups than L. natalensis at all the temperatures except 
18°C at which temperature the latter species outnumbered it. At. 2.5 months (Fig. 4) 
the numbers of mass groups had increased for both species but this was particularly 
noticeable for B. tropicus at 27°C where, already, 12 mass groups were recorded. 
The histograms in Fig. 4 moreover reveal that the mass groups had, from the time 
represented by Fig. 3, moved towards the right, i.e., in the direction of the heavier 
groups, noticeably faster in the case of B. tropicus than that of L. natalensis . At 
18°C, however, the latter species still had an advantage over the former. While the 
overall picture at 3.5 (Fig. 5) months was more or less similar to the one at 2.5 months, 
with L. natalensis maintaining its advantage at 18°C where 14 mass groups could be 
recorded, this species started gaining onß. tropicus also at 15°C. 



PRINSLOO and VAN EEDEN 



83 




AGE 



; - Commencement of egg deposition 



FIG. 1. Graphic presentation of the average growth rates per month of populations of Bulinus 
tropicus reared at constant temperatures. 



,.15° С 
18°C 



21°C 




AGE 



3 5 
N MONTHS 



FIG. 2. Graphic presentation of the average growth rates per month of populations of Lymnaea 
natalensis reared at constant temperatures. 



The most interesting novelty at 4.5 months (Fig. 6) was the large number of mass 
groups recorded for both species (16 each) at 21° C, the small number for Lymnaea 
natalensis at 25° С and the fact that, at 21° C, this species had gained on Bulinus tropi- 
cus with regard to mass increase. Towards the end of the experiment (Figs. 7, 8), 
however, the numbers of mass groups of B. tropicus had decreased considerably com- 



84 



PROC. FOURTH EUROP. MALAC. CONGR. 




25°C 



or ^J 

Ш 

S о 



■■'■ 




MASS IN MGM 



6 30 54 78 102 126 150 



21 °C 




MASS IN MGM 



6 30 54 78 102 126 150 



18°C 




FIG. 3. 
tropicus 



Mass distribution in experimental populations of Lymnaea natalensis (A) and Bulinus 
(B) reared at constant temperatures. Age 1. 5 months. 



< 

z 
</> о 



25°C 




MASS IN MGM 



6 30 54 78 102 126 150 174 198 222 246 270 

18 °C 

"" ■ A 

В 




21°C 




MASS IN MGM 



6 30 54 78 102 126 150 174 198 222 

15°C 






л 
в 



FIG. 4. Mass distribution in experimental populations of Lymnaea natalensis (A) and Bulinus 
tropicus (B) reared at constant temperatures. Age 2. 6 months. 



PRINSLOO and VAN EEDEN 



85 



TABLE 2. Number of mass groups and mass range (mgm/specimen) in experimental popu- 
lations of Bulinus tropicus and Lymnaea natalensis reared at different constant 
temperatures. 



Age in 
months 


Species 


A 
В 
ir 


mass groups 
mass range 
i mg/spec. 




27 


Temperature in 
25 21 


С 
18 


15 


1.5 


L. 


natalensis 


A 


mass groups 


4 




6 


4 


4 


_ 








В 


mass range 


6- 


42 


6-66 


6-42 


6-42 






B. 


tropicus 


A 


mass groups 


8 




8 


5 


1 


- 








В 


mass range 


6- 


114 


6-102 


6-54 


6-6 




2.5 


L. 


natalensis 


A 


mass groups 


6 




9 


8 


9 


_ 








В 


mass range 


6- 


102 


6-114 


6-90 


6-102 






B. 


tropicus 


A 


mass groups 


12 




8 


7 


5 


- 








В 


mass range 


62 


-198 


78-174 


54-126 


18-66 




3.5 


L. 


natalensis 


A 


mass groups 


_ 




8 


11 


14 


9 








В 


mass range 






18-126 


18-174 


18-210 


6-114 




B. 


tropicus 


A 


mass groups 


- 




13 


9 


8 


7 








В 


mass range 






78-258 


90-222 


30-126 


6-78 


4.5 


L. 


natalensis 


A 


mass groups 


_ 




3 


16 


12 


11 








В 


mass range 






78-102 


30-246 


30-270 


30-198 




B. 


tropicus 


A 


mass groups 


- 




9 


16 


10 


7 








В 


mass range 






114-270 


78-270 


30-210 


18-114 


5.5 


L. 


natalensis 


A 
В 


mass groups 
mass range 


- 




- 


12 
42-258 


13 
42-320 


14 
66-310 




B. 


tropicus 


A 

В 


mass groups 
mass range 


- 




- 


9 

78-282 


10 
30-320 


7 
54-166 


6.5 


L. 


natalensis 


A 
В 


mass groups 
mass range 


- 




- 


9 

54-222 


13 
102-342 


14 
138-354 




B. 


tropicus 


A 
В 


mass groups 
mass range 


- 




- 


8 
174-380 


8 
42-380 


7 
90-222 



pared with those of L. natalensis. This was particularly obvious at 15° С (Fig. 8) 
where no bulinid specimen of over 222 mg was still alive at the termination of the 
experiment. This contrasts strongly with the large numbers for L. natalensis at 18° 
and 15°C, viz., 13 and 14 respectively (Fig. 8). It is of interest to note that even at 5.5 
months the populations of both species still contained specimens which, at all the 
temperatures still in operation, had not yet grown to beyond 54 mg. 

The numerical data on which Figs. 3-8 are based are reproduced in Table 2, from 
which one gets the impression that whereas the number of mass groups tended to 
increase with age in Lymnaea natalensis, they reached a peak in Bulinus tropicus at 
4.5 months and then gradually decreased again towards 6.5 months. It is certainly 
tempting to conclude that the differentiation into different mass groups must in some 



86 



PROC. FOURTH EUROP. MALAC. CONGR. 



2 



27°C 



MASS IN MGM 
i i i i i i i i i i i i i 



6 30 54 78 102 126 150 174 198 

21 °C 




25°C 

o. 






A 


"^T 


1 в 


Э. 

MASS IN MGM 




6 30 54 78 102 126 150 ГЯ 


198 222 


2 - 18°C 






A 
В 



FIG. 5. Mass distribution in experimental populations of Lymnaea natalensis (A) and Bulinus 
tropicus (B) reared at constant temperatures. Age 3. 5 months. 



21 °C 





25°C 






A 




MASS 


IN MGM 




В 


6 


30 54 78 

18°C 


102 126 


150 174 198 222 


246 270 294 


' 


■"- 


■* 


* 


A 

В 




MASS IN MGM 
i i i i i p ' 



'piiiiii 

6 30 54 78 102 126 150 174 198 222 246 270 



15°C 






FIG. 6. Mass distribution in experimental populations of Lymnaea natalensis (A) and Bülinus 
tropicus (B) reared at constant temperatures. Age 4. 5 months. 



way have been correlated with conditions of accelerated growth. Observations ap- 
parently supporting this view are the following: (a) In both species the periods of 
maximum mass increase per month and the largest number of mass groups coincided. 
In L. natalensis this was after 2.5andinB. tropicus before 2.5 months, (b) The largest 



PRINSLOO and VAN EEDEN 



87 



21°C 


й^Т^- 


A 

В 


18°C 






-. -^ 




A 

H 
в 


15°C 






6 30 54 78 102 126 150 T 


1 ' 1 — 1 — 1 — lili — 1 1 

П 198 222 246 270 294 


A 

В 

iiii — i i 
318 342 365 



MASS IN MG M 



FIG. 7. Mass distribution in experimental populations of Lymnaea natalensis (A) and Bulinus 
tropicus (B) reared at constant temperatures. Age 5. 5 months. 

o. 



ГУ ■ 
CM - 



2 о 



21 "C 




18°C 




15°C 




6 30 54 78 102 126 150 174 198 222 246 270 294 318 342 366 380 
MASS IN MGM 
FIG. 8. Mass distribution in experimental populations of Lymnaea natalensis (A) and Bulinus 
tropicus (B) reared at constant temperatures. Age 6. 5 months. 

numbers of mass groups were often established at those temperatures which, also on 
other grounds, could be regarded as the most favourable for the species concerned. 
For B. tropicus these temperatures were 27° and 25°C for as long as the snails lived 
at these temperatures and 21° and 18°C from 4.5 months onwards. The corresponding 



88 PROC. FOURTH EUROP. MALAC. CONGR. 

temperatures for L. natalensis were 21° and 18°C and up to 4.5 months and 18° and 
15°C from then onwards. 

DISCUSSION 

The differences in growth rate at the same constant temperatures between Bulinus 
tropicus and Lymnaea natalensis lead to the same conclusions as were reached by 
Prinsloo & Van Eeden (1969) on the basis of the finite rate of increase, intrinsic 
rate of natural increase, nett reproductive rate and mean generation time determined 
for these species. The high growth rate of B. tropicus at 27°, 25° and 21° С underline 
the fact that this species must be well adapted to surviving under the semi -arid 
conditions which prevail in many parts of South Africa where summer temperatures 
are generally high and the available habitats are subject to intermittent drying up. 
These climatic conditions naturally call for the capacity to survive high temperatures 
and to grow and reproduce rapidly as soon as the temperature starts rising after 
winter. The findings for both species invalidate the assumption that different size 
groups in the same population necessarily represent different generations of the same 
species for at 6.5 months the mass per specimen ranged from 90 to 222 mg for B. 
tropicus and from 138 to 342 mg for L. natalensis in spite of the fact that none of the 
specimens could have differed in age more than 24 hours. A temperature of 15°C may, 
on the evidence of our data, certainly be regarded as suboptimal for B. tropicus. And 
yet, at the end of 6.5 months some of the specimens kept at this temperature had 
grown to 222 mg. Compared with the maximum mass of 380 recorded for any speci- 
men of B. tropicus in our experiment, a specimen of 222 mg could not, in our 
opinion, be described as dwarfed. In fact, excluding one small specimen, the sizes of 
the specimens at 15°C and 6.5 months ranged from 162 to 222 mg so that the modal 
class specimens although admittedly smaller than at the higher temperatures, could 
still be described as fair sized. 

SUMMARY 

Five populations each of Bulinus tropicus and Lymnaea natalensis were reared at 
constant temperatures of 27°, 25°, 21°, 18° and 15°C. The 2 species differed notice- 
ably in their growth response to the different temperatures and the resulting differen- 
tiation into different mass groups. 

ACKNOWLEDGEMENTS 

This investigation was made possible by financial assistance received from the 
South African Council for Scientific and Industrial Research. 

LITERATURE CITED 

PRINSLOO, J. F. & VAN EEDEN, J. A., 1969, Temperature and its bearing on the 
distribution and chemical control of freshwater snails. S. Afr. med. J., 43: 
1363-1365. 



MALACOLOGIA, 1973, 14: 89-91 

PROC. FOURTH EUROP. MALAC. CONGR. 

STUDIES ON THE PERMEABILITY OF THE SEPTATE JUNCTION 
IN THE KIDNEY OF HELIX POMATIA L. 

P. F. Newell and J. M. Skelding 

Department of Zoology, Westfield College 
London University, NW3 1ST, U.K. 

It has long been suspected that the snail kidney is a functional analogue of the verte- 
brate glomerular nephron (Vorvohl, 1961; Martin, Stewart & Harrison, 1965). It is 
clear that in some gastropod molluscs the primary filtration process occurs in the 
heart (Picken, 1937; Van Aardt, 1968; Bonga & Boer, 1969). Recently Andrews & 
Little (1971) have provided the first ultrastructural evidence for the presence of 
podocytes in the epithelium covering the outer (pericardial) surface of the ventricle 
in the terrestrial prosobranch, Potería. These are similar to the podocytes of Bow- 
man's capsule in the vertebrate kidney. The ultra-filtrate is conveyed to the kidney 
through the reno -pericardial canal. 

In pulmonate land snails primary urine formation takes place in the kidney sac, 
but a recent ultra-structural survey of the kidney sac of Achatina achatina (Skelding, 
1972a, b) failed to reveal any structural equivalent of the vertebrate glomerular 
podocytes. This study showed that the cells of the kidney sac (nephrocytes) are joined 
by septate desmosomes composed of an intermediate junction and a septate junction. 
In the intermediate junction the intercellular space is patent, whereas in the septate 
junction the lateral plasma membranes are joined across the intercellular space by 
a series of regularly spaced bars, or septae. It is widely held that septate desmosomes 
prevent the movement of particles, including ions and water through the intercellular 
spaces between adjacent cells. If this is so, and if there is no specialised filtration 
site, by what route does fluid leave the blood vascular system and make its way into 
the lumen of the kidney sac? Skelding has proposed that the assumption that septate 
junctions are invariably "tight" may be incorrect and that they do not form an im- 
penetrable barrier to fluid movement in the nephrocytic epithelium lining the kidney 
sac in A. achatina. The permeability of the septate junctions in the kidney sac of 
Helix pomatia to horse-radish peroxidase and lanthanum has been studied by Newell 
and Skelding (1972) to test this hypothesis. 

The permeability of the junction to horse-radish peroxidase 

Hydrated active snails, approximately 30 g fresh weight, received 100 mg of horse- 
radish peroxidase in 0.1 ml of distilled water by injection into the ventral sinus. The 
animals were sacrificed at timed intervals after the injection and slices of the kidney 
sac tissue were fixed by immersion in 2% gluteraldehyde in 100 гаМ /l sodium phos- 
phate buffer, pH 7.6, for 30 minutes. The tissue was washed overnight in buffer solu- 
tion and then incubated in 0.1% 3-3 4 diamino benzidine reagent containing 0.01% hydro- 
gen peroxide in 100 mM/l tris-HCl buffer at pH 7.6, according to the method of 
Karnovsky (1967). The tissues were postfixed in 1% osmium tetroxide in phosphate 
buffer for 2 hours. They were subsequently dehydrated, and embedded in TA AB resin« 
Some tissue samples were taken from snails which had not been previously injected 
with peroxidase. These control samples were incubated in exactly the same way as 
the peroxidase-injected material. 

Micrographs showed that the injected peroxidase leaves the blood capillary and 
passes into the connective tissue underlying the nephrocytes. The nephrocytic basal 

(89) 



90 



PROC. FOURTH EUROP. MALAC. CONGR. 



L KS 



0Дл^1о2ги\Ш UiU^rwvJljL 





Hey Au AFe HRP La 
^»- 



Large 



Sma 1 1 



FIG. 1. Diagram of the nephrocytic epithelium of a pulmonate land snail. The graph shows the 
mobility of various molecules through the epithelium from a blood capillary. In Achatina achatina 
the capillaries are permeable to colloidal gold and ferritin, but the gold is excluded from passage 
into the intercellular spaces between the nephrocytes by the basal lamina (Skelding, 1972a). In 
Helix pomatia the capillaries are permeable to peroxidase, which enters the intercellular spaces 
between the nephrocytes but is excluded from the septate junctions. Lanthanum penetrates the 
septate junctions. 

Au, colloidal gold; AFe, ferritin; ВС, blood capillary; bl, basal lamina; Ct, connective tissue; 
Hey, haemocyanin; HRP, horse-radish peroxidase; La, lanthanum; LKS, lumen of kidney sac; 
PC, pore cell; SD, septate desmosome; UC, urate crystal. 



lamina is permeable to peroxidase and the latter passes into the intercellular spaces 
between the nephrocytes. The peroxidase was not detected beyond the septate junction 
and was absent from the intercellular spaces between the septae (see diagram). 
Comparison with the controls showed that intrinsic peroxidase activity was confined to 
mitochondria. 

The permeability of the junction to lanthanum 

Active, hydrated snails, approximately 30 g fresh weight, were sacrificed and the 
kidney was perfused with a solution containing 2% gluteraldehyde and 1% lanthanum 
nitrate brought to pH 7.7 with NaOH. Small slices of the kidney were fixed for 2 hours 
in fresh fixative containing lanthanum. The tissues were then post -fixed for 2 hours 
in 2% osmium tetroxide solution containing lanthanum in cacodylate buffer, pH 7.7. 
Finally, the tissue was dehydrated in alcohol and embedded in TA AB resin. The 
sections were examined without staining with heavy metals. 

Lanthanum was clearly visible throughout the intercellular spaces between the 
nephrocytes. At the apex of the cells the lanthanum had, in some cases, penetrated 
through part, or the whole of, the septate region of the intercellular junction. Lanthanum 
was also infrequently present in the intermediate junction, which may mean that some 
areas of the septate junction are permeable to this molecule. Oblique sections of 
septate junctions infiltrated with lanthanum showed that the septae are parallel 



NEWELL and SKELDING 91 

corrugated sheets which seemed in all respects similar to those described from the 
gill of the fresh water mussel, Elliptio complanatus, by Gilula, Branton & Satir (1970). 

When lanthanum is applied to tissues at the time of fixation the results must be 
treated with caution; it cannot be assumed that the permeability of the tissues remains 
unaltered during fixation. However, the absence of peroxidase from the septate 
junction seems to imply that peroxidase molecules do not diffuse into the septate 
junction as a post-fixation artefact. The size of the particle determines whether or 
not it penetrates the junction. If this is so, then the kidney sac lamella is a series of 
barriers of decreasing porosity from the blood capillary to the apex of the nephrocytic 
epithelium. Skelding (1972a) showed that the blood capillaries within the kidney sac of 
Achatina achatina are impermeable to haemocyanin, but partially permeable to col- 
loidal gold and ferritin particles (ca. 100A diameter and 90A respectively). The basal 
lamina supporting the kidney sac cells is impermeable to colloidal particles yet 
permeable to ferritin, which penetrates the intercellular spaces only in the lower 
third of the cell height. 

The present study shows that smaller particles including horse-radish peroxidase 
(M.W. 40,000) can fill the whole of the intercellular space. Lanthanum, which is 
known to penetrate gaps as small as 20A, gains access to the lumen of the kidney sac. 
Thus, the fluid contained in the intercellular spaces between the nephrocytes ori- 
ginates from the blood, and might enter the urine by passage through localised areas 
of the septate junctions. A similar proposal has been made by Karnovsky (1967) to 
explain the formation of lymph by vertebrate capillaries. 

REFERENCES 

ANDREWS, E. & LITTLE, C, 1971, Ultrafiltration in the gastropod heart. Nature, 

Lond., 234(5329): 411-412. 
BONGA, S. E. W. & BOER, H. H., 1969, Ultrastructure of the reno-pericardial system 

in the pond snail Lymnaea stagnalis (L.)* Z. Zellforsch. mikrosk. Anat., 94: 

513-529. 
GILULA, N. В., BRANTON, D. & SATIR, P., 1970, The septate junction: A structural 

basis for intercellular coupling. Proc. natn. Acad. Sei. U.S.A., 67(1): 213-220. 
KARNOVSKY, M. J., 1967, The ultrastructural basis of capillary permeability studied 

with peroxidase as a tracer. J. cell Biol., 35: 213-236. 
MARTIN, A. W., STEWART, D. M. & HARRISON, F. M., 1965, Urine formation in a 

pulmonate land snail, Achatina fúlica. J. exp. Biol., 42: 99-123. 
NEWELL, P. F. & SKELDING, J. M., 1972, Permeability of the septate junction in the 

kidney of Helix pomatia L. (In press). 
PICKEN, L. E. R., 1937, The mechanism of urine formation in invertebrates. II. 

Excretory mechanisms in certain mollusca. J. exp. Biol., 14: 20-34. 
SKELDING, J. M., 1972a, Renal function in Achatina achatina (L.) and Helix pomatia 

L. Ph.D. thesis, University of London. 
SKELDING, J. M., 1972b, The structure of the kidney oí Achatina achatina. (In press). 
VAN AARDT, W. J., 1968, Quantitative aspects of the water balance in Lymnaea 

stagnalis (L.). Neth. J. Zool., 18: 253-312. 
VORVOHL, G., 1961, Zur Funktion der Exkretionsorgone von Helix pomatia (L.) und 

Archachatina ventricosa (Gould). Z. vergl. Physiol., 45: 12-49. 



MALACOLOGIA, 1973, 14: 93-96 

PROC. FOURTH EUROP. MA LAC. CONGR. 

STUDIES ON THE RENAL PHYSIOLOGY OF ACHATINA ACHATINA (L.) 

John M. Skelding 

Department of Zoology, Westfield College 
London, NW3, U.K. 

The kidney of the stylommatophoran pulmonate molluscs has attracted the attention 
of workers interested primarily in nitrogen metabolism; but the role of the renal 
organ in salt and water balance has received scant attention. The Stylommatophora 
are of considerable interest in that their renal physiology might usefully be compared 
with that of other invertebrates which have exploited the land habitat. Useful compari- 
sons can be made also with their close aquatic relatives, the freshwater Basommato- 
phora. 

In freshwater snails the first -formed, or primary urine, originates in the peri- 
cardium, by pressure filtration of the blood through the wall of the heart (Picken, 
1937; Bonga & Boer, 1969; Van Aaardt, 1968). The ultrastructural basis for this 
process in the terrestrial prosobranch Potería has recently been described by An- 
drews & Little (1971). In terrestrial pulmonates, urine formation takes place in the 
kidney sac. Vorvohl (1961) demonstrated that in Archachatina ventricosa and Helix 
pomatia, the primary urine can be collected from a catheter inserted into the kidney 
sac, while a catheter simultaneously inserted into the pericardium yields only a very 
meagre fluid flow. Martin, Stewart & Harrison (1965) demonstrated that when inulin 
is injected into Achatina fúlica, it appears in the urine at a similar concentration to 
that present in the blood. They showed also that when back pressure is applied to the 
ureter there is a resulting diminution in urine flow rate. The formation of urine 
ceases when the back pressure exceeds 12 cm of water. 

Taken together these observations appear to support the conclusion that the kidney in 
land snails functions in a similar manner to the vertebrate glomerular kidney; that is, 
filtration of the blood by hydrostatic pressure leads to the formation of a primary 
urine which is identical with the blood, except in the absence of compounds of very 
high molecular weight. The final urine is subsequently elaborated by reabsorptive 
and secretory processes. However, there are several objections to this conclusion. 

l)The appearance of the renal test substance, inulin, in the urine is probably not 
incontrovertible evidence that it is formed as a consequence of filtration under hydro- 
static pressure. The Malpighian tubule of Calliphora, which is known to form primary 
urine by a secretory process (Berridge & Oschman, 1969), is also able to excrete 
inulin, albeit with a U /в of 0.5 (M. Phillips, pers. comm.). The isolated salivary 
glands of Helix aspersa secrete saliva following addition of the hormone 5-hydroxy- 
tryptamine. When 14 С -carboxy- inulin is added to the bathing medium, it appears in 
appreciable quantities in the saliva (Skelding, unpubl.). Some secretory tissues are 
therefore permeable to inulin. 

2)Some secretory processes may be susceptible to applied back pressure. Ramsay 
(1954) has shown that the Malpighian tubules of Dixippus cease urine formation when 
the applied back pressure exceeds 20 cm of water. Maddrell (1969) has reported that 
back pressure lessens the rate of urine formation by the Malpighian tubules of 
Rhodnius, in vitro. 

Before we can be certain that the land snail kidney is a functional analogue of the 
vertebrate glomerular kidney, the following criteria should be satisfied, 
a) The primary urine and the blood should be identical in composition with respect 

(93) 



94 PROC. FOURTH EUROP. MALAC. CONGR. 

to ions and small organic molecules. 

b) The extent to which large molecules are prevented from entering the urine from the 
blood should be a function of their molecular size. 

c) Within the kidney, a morphological site or route should exist, where the blood and 
urine are brought into intimate proximity, and where filtration of the blood might take 
place. 

d) A hydrostatic pressure gradient in excess of the colloid osmotic pressure of the 
blood should exist across this site which favours the movement of fluid from the blood 
into the urine. 

In the case of the land snail kidney all of the above criteria remained to be demon- 
strated at the time of the initiation of the present study. The author has investigated 
aspects of the physiology and the ultrastructure of the kidney in Helix pomatia and 
Achatina achatina to determine whether they satisfy these criteria. Only those exper- 
iments with A . achatina are described here. 

Hydrated animals received injections of the renal test substance, inulin. Fluid 
samples were removed from the various regions of the kidney and ureter by means 
of silica micropipettes. A blood sample was also taken. The concentrations of Na + , 
K+, Ca++, Mg ++ , CI - and HC0 3 ~ were determined, with melting point and 14 C-inulin 
activity, in the urine and blood samples. The ionic composition, osmotic pressure and 
inulin concentration of the urine could be compared with identical parameters in the 
blood, and provided clues to the nature of the processes underlying the elaboration of 
the final urine. 

Pericardial fluid and primary urine in the kidney sac are similar in composition 
to the blood with respect to most ions, osmotic pressure and concentrations of inulin. 
Calcium and magnesium concentrations are elevated in the blood compared with the 
pericardial fluid and primary urine, possibly as a consequence of cation-binding by 
the blood proteins. These observations satisfy the first criterion, set out above. As 
the fluid moves along the ureter ions (mainly Na+ and Cl~) are reabsorbed together 
with some water, and the urine becomes progesssively more hypotonic compared with 
the blood. The final urine, in the distal region of the secondary ureter, represents 
two-thirds of the volume which entered the kidney in the form of primary urine. 
Approximately 86% of the calcium, 80% of the sodium and 64% of the chloride are re- 
absorbed. Potassium enters the urine in the secondary ureter, and there is an overall 
small net secretion of this cation into the urine. Bicarbonate ions persist in the final 
urine at a similar concentration to that present in the blood, so that this anion con- 
tributes significantly to the overall osmotic pressure of the final urine. Under con- 
ditions of hydration the osmotic pressure of the final urine is approximately one half 
that of the blood. 

A group of hydrated animals was injected with inulin and was subsequently subjected 
to desiccation until they had lost 10% of their total live weight. Samples of blood and 
urine from the various regions of the kidney were taken for analysis. The osmotic 
pressure and the concentration of all the measured anions and cations in the blood 
increase during dehydration. These increases are matched by similar increases in 
the ionic concentration of the pericardial fluid and the primary urine. The animals 
continue to form a strongly hypotonic urine which contains about twice the concentration 
of potassium present in the blood. Achatina achatina responds to dehydration by 
reabsorbing a larger proportion of the water from the primary urine. Almost 70% 
of the water, together with 90% of the sodium and chloride are reabsorbed from the 
primary urine, while 80% of the potassium is excreted. 

Herbivorous animals, whose main dietary cation is potassium, are likely to find 
sodium, the major blood cation, in short supply in their food. If, during dehydration, 
the animals were to excrete sufficient sodium in the urine to keep the blood concen- 



SKELDING 95 

tration constant, upon rehydration a similar amount of sodium would have to be in- 
gested. The animals do not form a hypertonic urine, and they continue to conserve 
salt when dehydrated, even though the salt concentration of the blood increases. 
Under natural conditions the animals may be alternately subjected to conditions of 
hydration and dehydration over short time intervals. By conserving salt even when 
they are dehydrated, the animals avoid the need to ingest large amounts of salt, when 
subsequently water becomes plentiful and the animals are rehydrated. The unusual 
tolerance of the tissues to varying salt concentrations is undoubtedly of considerable 
selective advantage to these animals. 

The ability of the kidney to discriminate between particles on the basis of their 
molecular size was tested as follows. Dextran molecules of 2 molecular size ranges 
were injected into the blood of 2 groups of experimental animals. The ability of the 
kidney to exclude these compounds from the urine was determined by comparing the 
concentrations of dextran in urine and blood (и/в ratio). Low molecular weight 
dextran (Mol.Wt. 16,000-19,000) enters the urine at a similar rate to inulin, that is, 
the и/В ratio is approximately 1. The U /в ratio of high molecular weight dextran 
(60,000-90,000 Mol. Wt.) in the primary urine of Achatina achatina is 0.58 ±0.05. 
(Mean ± S.D., 6 animals). Clearly a restriction to the movement of particles into 
the urine operates in the size range 19,000-90,000 Molecular weight. This is equivalent 
to an Einstein-Stokes radius of 30-40A. The high permeability of the snail kidney 
compared with vertebrate kidneys may be functionally related to the high molecular 
weight of the major blood protein, haemocyanin (Mol.Wt. 8.9 x 10 6 ). 

Electron microscopical investigations revealed that no direct structural analogue 
of the vertebrate glomerulus or of the basommatophoran epicardial podocytes exists 
in Achatina achatina. It is therefore concluded that fluid reaches the urinary space 
from the blood capillaries by crossing the nephrocytic epithelium which lines the 
kidney sac. The fluid which bathes the base of the nephrocytes is haemocyanin-free 
and presumably originates by ultrafiltration of the blood through the walls of the 
fenestrated capillaries in the so-called blood space. The basal lamina underlying the 
nephrocytes is impermeable to colloidal gold particles approximately 100A in diameter, 
but is permeable to ferritin molecules. Ferritin does not enter the final urine in 
significant amounts, so the basal lamina is probably too coarse a filter to be responsible 
for the final filtration process. The further movement of ferritin is restricted by the 
extracellular mucopolysaccharide which coats the basal and lateral plasma membranes. 
It is proposed that the septate junctions between the nephrocytes are "leaky" and con- 
tain pores or discontinuities in their structure through which fluid from the inter- 
cellular spaces gains access to the urinary space (Skelding, 1972). 

The kidney sac epithelium may be functionally analogous to the vertebrate capillary 
endothelium; in the latter, the so-called tight junctions {zonula occludens) contain 
pores through which lymph passes into the interstitium. It might be speculated that 
the degree of leakiness of the septate junction in various epithelia is related to their 
physiological function. Where highly permeable epithelia are required, the intercellular 
junctions are entirely absent (visceral epithelium of Bowman's capsule, crayfish coelo- 
mosac, epicardial cells in Potería). Where a diffusely permeable epithelium is required 
(nephrocytes of Achatina, vertebrate myocardial and skeletal capillaries) the intercellu- 
lar junctions may contain pores. This hypothesis has been tested by Newell & Skelding 
(1973a, b). Frömter & Diamond (1972) have recently shown that in many vertebrate 
fluid-transporting epithelia the route of passive ion permeation is through the so-called 
tight junctions. Moreover, these authors have also suggested that water and small 
non-electrolytes, including inulin, may pass across epithelia by the same route. 

That a filtration process is involved in urine formation in the land snail kidney 
seems undeniable. At the present time there is little direct evidence that filtration 



96 PROC. FOURTH EUROP. MALAC. CONGR. 

is brought about by arterial pressure. The possibility that a secretory process is 
involved cannot be entirely eliminated. 

The role of the ureter in reabsorption is reflected in its ultrastructure. The epi- 
thelium lining the duct is composed of cells which bear an apical microvillous border. 
The lateral plasma membranes are thrown into vertical folds which are continuous 
with invaginations of the basal plasma membrane. Adjacent cells therefore inter- 
digitate in a complex fashion. The cytoplasmic folds contain large numbers of mito- 
chondria and considerable accumulations of glycogen. The cells thus support a series 
of vertical, extracellular, fluid-filled channels. Diamond & Bossert (1967) have pro- 
posed that intercellular channels in fluid-transporting epithelia support standing os- 
motic gradients and are the route whereby fluid passes across the cells. 

REFERENCES 

ANDREWS, E. & LITTLE, C, 1971, Ultrafiltration in the gastropod heart. Nature, Lond., 

234(5329): 411-412. 
BERRIDGE, M. & OSCHMAN, J., 1969, A structural basis for fluid secretion by Mal- 

pighian tubules. Tissue Cell, 1: 247-272. 
BONGA, S. E. W. & BOER, H. H., 1969, Ultrastructure of the reno-pencardial system 

in the pond snail Lymnaea stagnalis (L.). Z. Zellforsch. mikrosk. Anat., 94: 

513-529. 
DIAMOND, J. M. & BOSSERT, W. H., 1967, Standing-gradient osmotic flow. A mecha- 
nism for coupling of water and solute transport in epithelia. J. gen. Physiol., 50: 

2061-2083. 
FRÖMTER, E. & DIAMOND, J., 1972, Route of passive ion permeation in epithelia. 

Nature, Lond., New Biol., 235: 9-13. 
MADDRELL, S. H. P., 1969, Secretion by the Malpighian tubules of Rhodnius. The 

movements of ions and water. J. exp. Biol., 51: 71-97. 
MARTIN, A. W., STEWART, D. M. & HARRISON, F. M., 1965, Urine formation in a 

pulmonate land snail, Achatina fúlica. J. exp. BioL, 42: 99-123. 
NEWELL, P. F. & SKELDING, J. M., 1973a, Studies on the permeability of the septate 

junction in the kidney of Helix pomatia. Proc. 4thEurop. Malac. Congr. Malacologia, 

14: 89-91. 
NEWELL, P. F. & SKELDING, J. M., 1973b, Permeability of the septate junction in 

the kidney of Helix pomatia L. (In press). 
PICKEN, L. E. R., 1937, The mechanism of urine formation in invertebrates. U. 

Excretory mechanisms in certain mollusca. J. exp. Biol., 14: 20-34. 
RAMSAY, A., 1954, Active transport of water by the Malpighian tubules of the stick 

insect Dixippus morosus (Orthoptera, Phasmidae). J. exp. Biol., 31: 104-113. 
SKELDING, J. M., 1972a, Renal function in Achatina achatina{h.) and Helix pomatia L. 

Ph.D. thesis, University of London. 
SKELDING, J. M., 1972b, The structure of the kidney in Achatina achatina (L.) (In 

press). 
VAN AARDT, W. J., 1968, Quantitative aspects of the water balance in Lymnaea 

stagnalis (L.). Neth. J. Zool., 18: 253-312. 
VORVOHL, G., 1961, Zur Funktion der Exkretionsorgone von Helix pomatia L. und 

Archachatina ventricosa (Gould). Z. vergl. Physiol., 45: 12-49. 



MALACOLOGIA, 1973, 14: 97-106 

PROC. FOURTH EUROP. MALAC. CONGR. 

MICRO-BIOCHEMICAL AND PHYSIOLOGICAL STUDIES ON AN IDENTIFIED 
SEROTONERGIC NEURON IN THE SNAIL HELIX POMATIA 

Neville N. Osborne *■ 

Wellcome Laboratories of Pharmacology 
Gatty Marine Laboratory, University of St. Andrews, Scotland 

INTRODUCTION 

The work described in this paper is divided into 2 parts, the 1st of which deals with 
the identification of a giant serotonergic neuron in the metacerebral ganglia of Helix 
pomatia. This work was initially undertaken to measure the serotonin content of an 
identifiable neuron and also to study the precise subcellular localisation of the amine. 
The 2nd part of the paper is concerned with the composition of amino acids and related 
substances in the giant metacerebral serotonergic cell. To demonstrate the chemical 
heterogeneity of nerve cells, the amino acids and related substances were also deter- 
mined in the circumoesophageal ganglia and a giant neuron of the buccal ganglia which 
lacks serotonin. 

I. LOCALISATION AND ESTIMATION OF SEROTONIN IN THE GIANT 
METACEREBRAL CELL 

It is important to know the exact localisation of serotonin (5-hydroxytryptamine) in 
nervous tissue in order to interpret its physiological role. Previous work on nervous 
tissue of molluscs (see Cottrell & Laverack, 1968; Cottrell & Osborne, 1970) shows 
that serotonin is probably localised in small granular vesicles in the cell cytoplasm, 
but confirmation of this has proved difficult, mainly because it has not been possible 
to study tissue known to contain serotonin and no other monoamines. However, infor- 
mation is now available (Cottrell & Osborne, 1970) describing the serotonin distribu- 
tion in the cytoplasm of a neuron situated in the metacerebral ganglion of the slug 
Limax maximus. It was decided to investigate the localisation of serotonin in the 
analogous cells of the metacerebral ganglia of the snail Helix pomatia. 

Using standard methods of amine-fluorescence histochemistry (Corrodi & Jonsson, 
1967), a pair of giant yellow fluorescing cells can be localised in the metacerebral 
ganglia of Helix pomatia (Fig. 1). These cells had already been discovered by Osborne 
& Cottrell in 1971. The first object was to ensure that this yellow fluorescence was 
specific to serotonin and this was judged by the criteria of colour, reducibility, fading 
and absence without paraformaldehyde sublimation. Since some neurons in the snail 
are thought to contain serotonin as well as dopamine (Kerkut, Sedden & Walker, 1967), 
it was decided to examine the nature of the amine-fluorescence in giant metacerebral 
neurons of snails which had been pretreated with drugs known to interfere with the 
metabolism of different monoamines. The results of this study are shown in Table 1, 
and they support the view that serotonin is localised in the giant neurons and further- 
more that the neurons do not contain any primary catecholamines. 



Present address: Max- Planck- Institut für Experimentelle Medizin, Arbeitsgruppe Neurochemie, 
3400 Göttingen, Hermann-Rein Strasse 3, Germany. 



(97) 



98 



PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 1. Section through a metacerebral ganglion of Helix pomatia processed by the histochemical 
method for demonstrating monoamines. Situated near the giant serotonergic neuron (large arrow 
head) which appears yellow in colour is a group of small green fluorescing cells (small arrow 
heads). Parts of the neuropile (n) contain green-yellow fluorescing fibre. (The bar represents 
100 p.) 




C-1 ml 
cell extracl 



FIG. 2. Response of an isolated Helix aspêrsa heart to serotonin, to snail saline, to an extract 
prepared from individually isolated giant serotonin-containing cells and to a similarly prepared 
extract from an equivalent number of non-fluorescing cells from the buccal ganglia (control). 

Using an isolated snail heart preparation which is known to be very sensitive to 
serotonin but insensitive to catecholamines (Cottrell & Osborne, 1969), the serotonin 
content in individually dissected neurons was measured (Fig. 2). From the results 
of a number of experiments the amine content was estimated at 0.6 ng/cell. This 
result was substantiated using a microchromatographic method (Osborne, 1971). In 
this procedure the brains from 4-8 animals are perfused with radioactive 5-hydroxy- 
tryptophan for at least 7 hours, the giant neurons then dissected and chromatographed. 
Chromatography was performed on 3x3 cm polyamide layers (Carl Schleicher & 
Schüll) in an ascending fashion, using either methyl acetate/isopropanol/ ammonia 






OSBORNE 



99 



TABLE 1. Summary of the effects of various drugs on the yellow fluorescence of the serotoner- 
gic neuron of Helix pomatia. Two mg of each drug were administered over a period 
of 30 hours before observation. 



Name of drug 


Effects 


Effect on yellow fluorescence 
of giant cell 


Reserpine 




Depletes amines from molluscan 
nervous tissue 


All fluorescence eliminated 


p-Chlorophenyl- 


Reduces 5- HT content by inhibiting 


Colour of fluorescent still 


alanine 




the enzyme tyrosine hydroxylase 


yellow although intensity 






in vertebrates. 


reduced 


a- methyl- m- 


-tyrosine 


Reduces CA content by inhibiting 


No change in colour and 






the enzyme tyrosine hydroxylase 


intensity of fluorescence 






in vertebrates 




5-HTP 




Precursor of 5- HT in molluscs 


Intensity of yellow 
fluorescence increased 


DOPA 




Precursor of CA's in molluscs 


No change in colour and 
intensity of fluorescence 


Nialamide 




Monoamine oxidase inhibitor in 


Slight increase in intensity 






vertebrates 


of yellow fluorescence 


NSD 1024 




DOPA decarboxylase inhibitor in 


Yellow fluorescence very 






molluscs 


slightly reduced 



25% (9:7:5) or butanol/chloroiorm/acetic acid (4:1:1), exposed to formaldehyde vapour 
and viewed under ultraviolet light. By scraping off the spot corresponding to different 
substances and counting the radioactivity associated with each of them, it became 
clear that the giant metacerebral cells take up radioactive 5 -hydroxy tryptophan and 
convert part of it to serotonin. 

Electron microscopy of the cells' cytoplasm revealed, as in Limax maximus (Cottrell 
& Osborne, 1970), the presence of large numbers of vesicles (Fig. 3a) together with 
elongated mitochondria, lysosome-like particles and other structures reported in 
molluscan neurons. Tissue fixed and processed by the method of Wood (1965, 1966) 
for detecting amines, contained electron dense reaction products in the small granules 
(Fig. 3) and, in some instances, in the lysosome-like particles. Prior injection of 
reserpine or p-chlorophenylalanine greatly reduced the number of granules in the 
serotonin-containing cell. 

DISCUSSION 



For the following reasons it is concluded that of all the monoamines, serotonin alone 
was present in giant metacerebral cells. Firstly, when processed by amine-histo- 
chemistry the giant neuron fluoresced yellow, an indication of serotonin, and the 
fluorescence formed was relatively unstable to ultraviolet light. Secondly, pretreat- 
ment of snails with drugs known to interfere with the metabolism of different mono- 
amines showed that the yellow fluorescence in the cytoplasm of the neuron was derived 
solely from serotonin. Thirdly, extracts from giant neurons could take up radioactive 
5 -hydroxy tryptophan and convert it to a substance which in 2 different solvents has 
the same chromatographic mobility as pure serotonin. 



100 PROC. FOURTH EUROP. MALAC. CONGR. 

A . . в '..• ... 



1W 






m- 

*- Щг ■ , 

Wv>>\.Vy4 

• ■ 

* p » 



« 



*, 



v • * 












FIG. 3. A, Electron micrograph of part of the cytoplasm from a giant serotonin cell fixed in 
glutaraldehyde and osmium and stained with lead citrate and uranyl acetate. The most conspicu- 
ous organelles in the cytoplasm are small granular vesicles (v) which have an average diameter 
of 60-120 nm, mitochondria (m), and lysosome-like structures (1). B, A similar part of another 
giant serotonin cell processed by the Wood's method. The electron-dense deposits represent 
sites of serotonin (localisation). These are the same size as the centres of the granular vesicles. 
(The bar represents 0. 5 \x. ) 

From a number of bioassay and chromatographic experiments the serotonin content 
of a single cell was estimated to be 0.6 ng. Since the total volume of the giant cell of 
Helix is about 1.2 nl and the cell's nucleus, which contains no serotonin, occupies about 
l/5 of this, it is estimated that the concentration of serotonin in the cytoplasm of the 
cell soma is 3.5xl0" 3 m. This concentration is of the same value as that calculated to 
exist in the giant cell of Limax maximus (Cottrell & Osborne, 1970). 

The localisation of serotonin in granules in the cytoplasm of the giant neuron of 
Helix pomatia is like that already observed in the giant serotonergic neuron of Limax 
maximus (Cottrell & Osborne, 1970). Granules of similar dimensions have been 
suggested to bind catecholamines and serotonin in nerves of the snail heart (Cottrell 
& Osborne, 1969), catecholamines in bivalve ganglia (Cottrell, 1967) and serotonin in 
the Retzius cell of the leech (Rude, Coggeshall & Van Orden, 1969). It is therefore 
suggested that serotonin is sequestered within the small granules. 



OSBORNE 101 

Preparations stained for the ultrastructural localisation of amines only rarely showed 
dense reaction products in the lysosome-like particles. A detailed study was not 
undertaken as in the case of Limax maximus, where a seasonal variation in the local- 
isation of the amine was observed (Cottrell & Osborne, 1970). In connection with this 
observation it was often noticed that tissue fixed and stained by standard methods of 
electron microscopy showed the occurrence of small granulated vesicles within the 
lysosome-like structure of the giant serotonergic cell. 

II. AMINO ACIDS AND RELATED COMPOUNDS IN ISOLATED NEURONS 

Appreciable amounts of amino acids occur in the nervous system. It is generally 
accepted that these are predominantly concerned with general metabolic processes 
and with the maintenance of water and ion distributors across cellular membranes. 
However certain amino acids may also function as synaptic transmitters. Recent 
papers catalogue the many instances where particular amino acids have been inferred 
to be potential transmitter substances. 

Neuhoff and co-workers (for details and references see Osborne, Briel & Neuhoff 
(1971) and Osborne (1972)) have recently described a microchromatographic method 
for the detection of amino acids in as little as 0.1 mg of nervous tissue. The method 
involves the reaction of the -OH or -NH 2 groups of amino acids and related substances 
with dansyl chloride (l-dimethylamino-naphthalene-5-sulfonyl-chloride) to form in- 
tensely fluorescent dansyl substances which can then be separated by microchroma- 
tography using certain solvent systems. This process detects as little as 1 pico mole 
of amino acid, which is extremely sensitive compared with other methods. This was the 
method used to analyse the distribution of amino acids and related substances in the 
brain, the metacerebral serotonergic giant neurons and a pair of non-serotonergic 
giant neurons from the buccal ganglia of Helix pomatia. The aim of this study was 
to reveal the heterogeneity of neurons with the snail brain with respect to content of 
amino acids and related substances. 

Radioautograms and maps showing the occurrence of 14 C-dansylated substances 
in the brain of Helix are shown in Fig. 4. The radioactivity associated with each spot 
is shown in Table 2. A number of points of interest concerning the amino acid distri- 
bution in the brain have been discussed elsewhere (Osborne, Briel & Neuhoff, 1971), 
but of special significance is the occurrence of GABA, which had previously been 
thought to be absent from gastropod tissues. 

A comparison of the amino acids and related substances in the brain, and of the 
metacerebral serotonergic neurons and the nonserotonergic neurons in the buccal 
ganglia is shown in Table 2. Generally the distribution of dansylated substances in 
the cell types is similar; GABA for example is present in each but in low concen- 
trations. The serotonergic cell however contains less ornithine and more glycine 
than the buccal cells. 

The results also show the existence of high levels of serotonin in the metacerebral 
giant cells when compared with the whole brain, and confirm the absence of the amine 
in the buccal cells. In this connection, the presence of the unknown substance (spot 
15) is of interest, for it occurs in large amounts in the serotonergic cell and to a 
lesser extent in the whole brain. Initial experiments suggested that the substance 
could be 5 -hydroxytryptophan. It is known that the serotonergic neurons can take up 
tritiated 5 -hydroxytryptophan and convert it to serotonin. 

The occurrence and distribution of 5 -hydroxy indole in gastropods would seem to 
indicate that this substance is a metabolite of serotonin. Besides occurring in the 
whole brain and, to a greater extent, in the serotonergic neurons, 5 -hydroxy indole 
is also present in the integument of the slug Avion ater (Osborne, Briel & Neuhoff, 



102 




MALAC. CONGR. 



027 & 


C^> ® 


cs> 






34 14 GD 


CJ> 




0^ 

18 




19 » 

6l«-NH^ 


33 




® 


Об 




s^P*/) 


07 ¿ 




^л22-27 1 /I 


9 CP cs^c 


4 


>L_>^i 




В 



12 


1« 

c^ 7 


Э 30 


11 

О 

10 




9 
CD 




О 


31 




<?&> CXPC 


^_^ 4 


хЭ4 



FIG. 4. Autoradiograms of microchromatograms and maps of substances in the brain (circum- 
oesophageal ganglia and connectives) of Helix pomatia after having reacted with l^C-dansyl- 
chloride. A, After chromatography in 2 systems; B, after chromatography in 3 systems. The 
direction of chromatography is indicated by the arrows. First direction water/formic acid 
(100:3), 2nd direction benzene/acetic acid (9:1), 3rd direction ethyl acetate/methanol/acetic acid 
(20:1:1). Each microchromatogram measures 3x3 cm. The numbers on each map corresponding 
to the dansyl compounds are shown on Table 2. Unmarked spots on chromatograms belong to 
impurities of l^ç-dimsyi-chioria'e. 



1971), in which part waste products of metabolism are often present. It is worth 
noting that attempts to detect the closely related substance, 5 -hydroxy indole acetic 
acid, in gastropod nervous tissues have proved unsuccessful (Osborne & Cottrell, 
1970). 



OSBORNE 



103 



TABLE 2. Composition of dansylated compounds when separated by microchromatography on 
polyamide layers. Results expressed as residues per 100 total residues. 



Spot 
No. 


Substances 


Brain 


Metacerebral 
serotonergic neuron 


Buccal non- 
serotonergic neuron 


1 


Starting point 


- 


- 


- 


2 


Unknown substance 


- 


- 


- 


3 


Taurine 


0.67 


- 


- 


4 


Dansyl-OH 


- 


- 


- 


5 


N-Tyrosine 


0.31 


1.71 


1.11 


6 


Tryptophan 


0.36 


1.91 


0.31 


7 


N-Serotonin 


0.42 


8.63 


- 


8 


Ornithine 


1.09 


3.01 


1.52 


9 


Bis-lysine 


0.42 


0.83 


2.88 


10 


Phenylalanine 


1.79 


3.39 


3.98 


11 


Leucine 


1.31 


2.46 


4.32 


12 


Isoleucine 


0.88 


1.44 


2.82 


13 


Bis-Histidine 


1.64 


- 


- 


14 


Bis-Tyrosine 


0.31 


0.31 


0.19 


15 


Unknown substance (5-HTP?) 


0.47 


5.68 


- 


16 


Proline 


0.72 


2.77 


2.81 


17 


Valine 


1.01 


1.38 


4.03 


18 


Methionine 


0.73 


0.69 


0.66 


19 


GABA 


0.38 


0.30 


0.65 


20 


Glycine 


3.61 


6.07 


7.38 


21 


Alanine + Dansyl-NH 2 


17.97 


30.79 


31.72 


22 


Glutamine + Threonine 


4.11 


3.06 


3.26 


23 


Asparagine + Serine 


3.0 


2.21 


3.01 


24 


Argenine , e - Lysine , 
a-amino-histidine and cystine 


42.72 


7.16 


9.36 


25 


Aspartic Acid 


1.67 


0.36 


0.49 


26 


Glutamic Acid 


5.03 


1.10 


1.57 


27 


Bis-Serotonin 


0.34 


0.63 


- 


28 


5- Hydr oxyindole 


0.72 


0.61 


- 


29-37 


Unknown substances 


8.32 


13.50 


18.23 



104 PROC. FOURTH EUROP. MALAC. CONGR. 

DISCUSSION 

It has been stressed that in order to understand more about the nervous system, 
chemical analysis must be done on repeatedly identifiable isolated neurons rather than 
on brain tissue, which often contains a heterogeneous population of neurons as well 
as glia and muscle tissue (Rose, 1968; Giacobini, 1969). The 1 giant serotonin- 
containing neuron in each metacerebral ganglion of Helix pomatia is known to make 
direct synaptic contact with at least 2 of the 3 repeatedly identifiable giant neurons 
which lack biogenic amines in the buccal ganglia (Cottrell, 1970a). All the available 
data suggest that the serotonin within these metacerebral neurons is used as a trans- 
mitter substance (Cottrell, 1970a, b; Cottrell & Osborne, 1970). The giant metacere- 
bral neuron and the buccal neuron therefore represent 2 different types of nerve cells. 

The most striking feature of these results is the high level of serotonin, 5 -hydroxy- 
indole and unknown substance (5-hydroxytryptophan?) in the metacerebral cell, and to 
a lesser extent in the whole brain, yet their complete absence from the buccal cells. 
This observation confirms the chemical heterogeneity of neurons within the gastropod 
brain. The distribution of other dansylated substances in the serotonergic and buccal 
cells is similar but for 2 exceptions. The serotonergic cells contain less ornithine 
and more glycine than the buccal cells. The significance of this discovery has still to 
be established. 

Finally mention must be made of the exact chemical content of each cell type. Iso- 
lation of cells by free-hand dissection can incur a number of errors, particularly from 
contamination. Furthermore, the cell membrane can be damaged during the dissection, 
thus allowing leakage of chemicals from the cells and subsequently destroying the 
integrity of the neuron. There is also evidence that methylene blue causes 'release' 
of chemicals from the cells (for details see Briel, Neuhoff & Osborne, 1971). It is 
for these and other reasons that a further number of experiments are required before 
deciding upon the exact chemical content of each cell type. In practice this might 
prove impossible should the chemical content of each neuron depend upon the activity 
of the individual snail. 

SUMMARY 

There is a giant serotonin-containing neuron in the metacerebral ganglion of the 
snail Helix pomatia. Further evidence for the presence of serotonin and the absence 
of catecholamines was obtained by observing the effects of different drugs on the 
amine fluorescence. Moreover, biological assay and microchromatography of cell 
extracts provided independent evidence for the existence of serotonin in the neurons, 
and the amount of amine was estimated at 0.6 ng/cell. The serotonergic neurons were 
also shown to take up tritiated 5-hydroxytryptophan and to convert the substance to 
serotonin. Results from electron microscopic cytochemistry revealed that serotonin 
is sequestered in small granular vesicles and also sometimes associated with lyso- 
some-like particles. 

Microchromatography of dansylated substances in the brain, the metacerebral 
serotonergic neurons and the non-serotonergic neurons in the buccal ganglia disclosed 
the chemical heterogeneity of neurons within the snail brain. 5 -hydroxy indole, sero- 
tonin and an unknown substance were all present in the metacerebral cells, and to a 
lesser extent in the brain, but absent from the buccal cells. The serotonergic meta- 
cerebral cells also contained less ornithine and more glycine than the buccal cells. 
Generally, however, the distribution of the other amino acids was similar in both cell 
types. 



OSBORNE 105 

ACKNOWLEDGEMENT 

The work reported in the 1st part of this paper was carried out in collaboration 
with Dr. G. A. Cottrell to whom the author is gratefully indebted. The work in the 
2nd part of the paper was accomplished in conjunction with Professor V. Neuhoff and 
Dr. G. Briel. The author is also grateful to the Royal Society of London for a travel 
grant. 

REFERENCES 

BRIEL, G., NEUHOFF, V. & OSBORNE, N. N., 1971, Determination of amino acids in 
single identifiable nerve cells of Helix pomatia. Intern. J. Neuroscience, 2: 129- 
136. 

CORRODI, H. & JONSSON, G., 1967, The formaldehyde fluorescence method for the 
histochemical demonstration of biogenic monoamines. J. Histochem. Cytochem., 
15: 65-78. 

COTTRELL, G. A., 1967, Amines in molluscan nervous tissue and their subcellular 
localisation. Sym. Neurobiol. Inverts., 9: 353-364. 

COTTRELL, G. A., 1970a, Direct postsynaptic responses resulting from stimulation 
of serotonin-containing neurons. Nature, Lond., 225: 1060-1062. 

COTTRELL, G. A., 1970b, Actions of LSD-25 and reserpine on a serotonergic synapse. 
J. Physiol., Lond., 208: 28-29. 

COTTRELL, G. A. & LAVERACK, M. S., 1968, Invertebrate Pharmacology, Ann. Rev. 
Pharmac, 8: 273-298. 

COTTRELL, G. A. & OSBORNE, N. N., 1969, Localisation and mode of action of cardio- 
excitatory agents in molluscan hearts. In: Comp. Physiol, of the heart. Current 
trends. Experientia, Suppl. 15: 220-231. 

COTTRELL, G. A. & OSBORNE, N. N., 1970, Serotonin: Subcellular localisation in an 
identified serotonin containing neuron. Nature, Lond., 225: 470-472. 

GIACOBINNI, E., 1969, Chemistry of isolated invertebrate neurons. In: Handbook of 
Neurochem. Ed. by A. Lajtha. Vol. II, 195-234. Plenum Press, London. 

KERKUT, G. A., SEDDEN, С. В. & WALKER, R. J., 1967, Uptake of DOPA and 5- 
hydroxy tryptophan by monoamine -forming neurons in the brain of Helix as persa. 
Comp. Biochem. Physiol., 23: 159-162. 

OSBORNE, N. N., 1971, A microchromatographic method for the detection of biologi- 
cally active monoamines in isolated neurons. Experientia, 27: 1502-1503. 

OSBORNE, N. N., 1972, Serotonin, free amino acids and related substances occurring 
in the blood and nervous tissue of Helix aspersa. Comp. gen. Pharmacol. ,3: 171-177. 

OSBORNE, N. N. & COTTRELL, G. A., 1970, Occurrence of noradrenaline and meta- 
bolites of primary catecholamines in the brain and heart of Helix. Comp. gen. 
Pharmacol., 1: 1-10. 

OSBORNE, N. N. & COTTRELL, G. A., 1971, Distribution of biogenic amines in the 
slug Limax maximus. Z. Zellforsch. mikrosk. Anat., 112: 15-30. 

OSBORNE, N. N., BRIEL, G. & NEUHOFF, V., 1971, Distribution of GABA and other 
amino acids in different tissues of the gastropod mollusc Helix pomatia, including 
in vitro experiments with 14 C-glucose and 14 C-glutamic acid. Intern. J. Neurosci., 
1: 265-272. 

ROSE, S. P. R., 1968, In: Applied Neurochemistry. Ed. by A. Davison & J. Dobbing. 
p 332-355, Blackwell, Oxford. 

RUDE, S., COGGESHALL, R. E. & VAN ORDEN, L. S., 1969, Chemical and ultrastruc- 
tural identification of 5 -hydroxy tryptamine in an identified neuron. J. Cell. Biol., 



106 PROC. FOURTH EUROP. MALAC. CONGR. 

41: 832-854. 
WOOD, J. G., 1965, Electron microscopic localisation of 5-hydroxytryptamine (5-HT). 

Tex. Rep. Biol. Med., 23: 828-837. 
WOOD, J. G., 1966, Electron microscopic localisation of amines in central nervous 

tissue. Nature, Lond., 209: 1131-1133. 



MALACOLOGIA, 1973, 14: 107-124 

PROC. FOURTH EUROP. MA LAC. CONGR. 

RESULTATS EXPERIMENTAUX SUR LA FIXATION DU ZINC -65 
PAR ANODONTA CYGNE A (LINNAEUS) 

L. Foulquier, P. Bovard et A. Grauby 

C.E.N. - Cadarache, France 

RESUME 

Le zinc-65 est un corps radioactif induit qui se retrouve principalement dans 
les déchets des reacteurs nucléaires; il est fortement concentré par les organis- 
mes vivants en particulier par les mollusques. Le développement des installa- 
tions nucléaires le long du Rhône a conduit les auteurs à étudier la fixation du 
zinc-65, (sous forme de chlorure), par Anodonta cygnea. 

Deux expériences sont décrites: La première concerne l'étude dynamique, par 
la mesure radioactive des animaux vivants, de l'absorption et de la désorption 
du zinc-65 par les anodontes en fonction de la variation de la teneur en zinc-65 
de l'eau. La fixation du zinc-65 par ces bivalves, qui semble être proportion- 
nelle à la teneur en zinc-65 de l'eau, est un phénomène rapide; on obtient un pic 
maximum d'activité dès le 3ème ou 4ème jour après la contamination. Dans un 
circuit d'eau inactive la perte du zinc par les anodontes est relativement lente; 
la période biologique est de l'ordre de 31 jours. 

La deuxième expérience est une étude de la fixation du zinc-65 par les dif- 
férents organes de l'Anodonte après avoir contaminé l'eau d'un aquarium con- 
tenant du sédiment. On constate une décroissance très rapide de l'activité de 
l'eau au profit du sédiment. Après 59 jours l'eau contient 0,2% de la quantité 
de zinc-65 introduite, les anodontes 6,2% et le sédiment 93,6%. 

Pendant toute l'expérience les activités spécifiques des tissus mous et de la 
coquille sont variables selon les individus mais demeurent à l'intérieur de cer- 
taines limites. L'activité des liquides internes baisse en fonction de la décrois- 
sance de l'activité de l'eau. L'hémolymphe a toujours une activité spécifique 
nettement supérieure à celle du liquide palléal et extrapalléal. En fonction de 
leurs activités spécifiques décroissantes, les organes internes se classent ainsi: 

1) branchies 4) bord du manteau 

2) palpes 5) masse viscérale 

3) siphons 6) masse musculaire 

Le facteurs de concentration, représentant le rapport entre l'activité de l'organe 
et l'activité de l'eau, à l'équilibre, sont en moyenne les suivants: 

Animal total - 955 Branchies = 7 840 

Coquille = 230 Palpes - 2 530 

Parties molles = 3 220 Siphons - 3 140 

Liquides internes - 30 Bord du manteau - 2 880 

Sang - 50 Masse viscérale = 2 620 

Masse musculaire - 2 470 

La distribution du radio-zinc dans l'organisme se répartit ainsi: 
Par rapport Par rapport 

à l'activité de l'animal total à l'activité des tissus mous 

Coquille - 10 % Masse viseérale = 40% 

Tissus mous = 88,5% Branchies et palpes - 35% 

Liquides internes - 1,5% Manteau - 15% 

Masse musculaire = 10% 

(107) 



108 PROC. FOURTH EUROP. MALAC. CONGR. 

Les Anodontes fixent très fortement le zinc-65 et peuvent éventuellement ser- 
vir comme indicateur du niveau de la contamination du milieu. La coquille 
retient essentiellement le zinc-65 par des mécanismes d'adsorption. Par con- 
tre les branchies et la partie externe du manteau sont des organes de fixation et 
de stockage préférentiels; l'hémolymphe semble jouer un rôle essentiel dans le 
transport du zinc. 

INTRODUCTION 

A cause de leurs besoins en eau les Centrales nucléaires s'installent le long des 
fleuves et des rivières utilisés comme exutoire naturel des grands volumes d' effluents 
faiblement radioactifs. Les corps ainsi rejetês rentrent dans les cycles biogéo- 
chimiques et il est donc particulièrement important d'étudier leur fixation par les 
organismes aquatiques. Nous avons vu que les bivalves constituent, de ce point de 
vue, des témoins biologiques intéressants [1]. Nous présentons ici quelques résultats 
expérimentaux concernant la fixation du zinc-65 par Anodonta cygnea (L.). 

Le zinc est un oligoêlément important en écologie [2]. Le zinc-65, qui peut servir 
de traceur pour l'étude du cycle du zinc stable, est un corps produit par la radio- 
activité induite à partir des sels dissous. Ce phénomène se réalise après les explosions 
nucléaires sousmarines. Par exemple, dans les îles Marshall, on décèle la présence 
de radioactivité un an à deux ans après les explosions et, en particulier dans les 
bivalves [3]. Mais on trouve aussi du zinc-65 dans les déchets des réacteurs nu- 
cléaires; d'importantes quantités de zinc-65 sont véhiculées par la Columbia River 
[4], et les teneurs sont parfois notables le long des côtes et dans les estuaires [5]. 

Par ailleurs, le zinc est un produit fortement concentré par les organismes d'eau 
douce ou marins [6] [7]. Les mollusques, en particulier, sont de bons indicateurs de 
la présence de zinc-65 [4] [7] [8] [9] [10]. 

CONDITIONS EXPERIMENTALES 

Les contaminations expérimentales sont réalisées avec du chlorure de zinc en 
solution HCl (N = 0.1) sans entraîneur (la teneur en zinc stable influe sur le niveau de 
la contamination des organismes). La période du zinc-65, émetteur Y , est de 245 
jours. Dans tous les résultats nous avons tenu compte de la décroissance physique 
du radioélément en effectuant les corrections nécessaires. 

Les mesures sont faites sur un sélecteur d'amplitude monocanal, (la sonde est 
constituée d'un syntibloc SC 3 N 50 1' 3/4 2"). 

L'eau est prélevée par pipettage, placée dans des tubes de 10 cm 3 et comptée 
directement dans un cristal -puits. La mesure des animaux s'effectue selon deux 
procédés différents; les courbes de la dynamique de la contamination et de la decon- 
tamination sont obtenues par la mesure des animaux vivants; à différents intervalles 
de temps les échantillons sont prélevés, lavés et comptés, de telle sorte que chaque 
point de la courbe représente une valeur moyenne; les animaux sont placés dans le 
compteur de manière à ce que les conditions de géométrie soient les plus voisines 
possibles. Pour les mesures réelles de l'activité, les organes sont disséqués, pesés 
frais 1 et placés dans les tubes de comptage, les coquilles sont préalablement broyées. 



1t 4. Poids frais . . 

A Les rapports sont en moyenne les suivants: 



Animal total = 4,5 Manteau z 17 Masse musculaire - 10 

Tissus mous - 10 Branchies = 7,7 Masse viscérale = 13 

Coquille - 1,1 



FOULQUIER, BOVARD et GRAUBY 



109 



1QOOO 



5.OOO; 



Activité de I eau 
( Des / miN / ce ) 
(Echelle logarithmique) 



IOOO., 



500.. 



100 




x— x— x — _ _ __ 



25 



50 



75 



80 



FIG. 1. Variations de la teneur en zinc-65de l'eau. 



Les aquariums expérimentaux sont climatisés à 16°C ± 1°C. Nous utilisons toujours 
la même eau et le même sédiment provenant du Rhône. L'eau renferme entre 3 et 
10 /Lig/litre de zinc et le sédiment entre 0,5 et 2 mg/lOO g. 

RESULTATS 

ETUDE DYNAMIQUE DE L'ABSORPTION ET DE LA DESORPTION DU ZINC -65 PAR 
LES ANODONTES 

Dans un aquarium contenant trente litres d'eau et du sédiment nous avons placé 
cinq anodontes. Après avoir laissé le bac se stabiliser pendant 15 jours nous avons 
entrepris l'expérience. Elle consiste à faire varier en fonction du temps la teneur 
en zinc-65 de l'eau et à suivre l'évolution de l'activité des anodontes. La Fig. 1 et 



110 PROC. FOURTH EUROP. MA LAC. CONGR. 

TABLEAU 1. Variations de la teneur de l'eau en zinc-65 en fonction du temps. 



Temps 


Des/min/cc 


Processus expérimental 




1 heure 


5 100 


— 1ère contamination 




6 heures 


1 500 






1 jour 

2 jours 


J+30 
270 
220 


(3,5 ^Ci/litre soit 
7 8OO Des/min/cc) 




7 


230 






8 " 


180 




9 jours ( 1 heure) 


4 830 


— 2ème contamination 


9 


' ( 6 heures) 


1 9^0 




10 « 


■ (36 » ) 


500 




11 ' 


' ( 2 jours) 


370 




i¿t ■ 

15 
16 


(5 " ) 
(6 " ) 

(7 " ) 


260 
230 
220 


(3,3 (jCi/litre soit 
7 ¿+00 Des/min/cc) 


17 


' (8 " ) 


210 




18 • 


(9 » ) 


220 




22 i 


(13 " ) 


190 




23 ' 


(16 " ) 


190 




29 


1 (20 ■■ ) 


190 




30 
30 


1 ( 1 heure) 
' ( 6 heures) 


9 500 
2 8*t0 


— 3ème contamination 


31 


1 ( 1 jour) 


1 510 




32 
35 
37 
A2 


' ( 2 jours) 

1 ( 5 jours) 

(7 " ) 

' (12 " ) 


810 
660 
590 
600 


(3,9 (jCi/litre soit 
8 9OO Des/min/cc) 


52 

56 ' 


(19 " ) 
(21 " ) 
(25 " ) 


530 
i+70 
^50 




59 ■ 


(28 " ) 


510 






60 jours 


) 


— -Décontamination 




I 

90 jours 


\ ГУ 


(Introduction des ano- 
dontes dans un circuit 
d'eau inactive) 



le Tableau 1 montrent le processus de l'expérience. Après chaque contamination 
l'activité de l'eau augmente très rapidement et décroît également vite ensuite. Il 
semble que Ton atteigne un état d'équilibre environ 30 jours après la contamination. 
Remarquons que chaque fois que l'on apporte du zinc-65 l'activité spécifique de l'eau 
se stabilise à un niveau plus élevé. Il doit se produire des phénomènes de saturation 
progressive au niveau du sédiment. Il s'en suit que plus le milieu reçoit de zinc-65 
plus les anodontes vivent dans une eau de radioactivité élevée et, par conséquent, 



FOULQUIER, BOVARD et GRAUBY 



111 



зол о . 



20.10 



5.10" 



Activibé d<zs Anodontes 

ps /min ) 
Échellá logarithm ique 




О 
U 
«у 

Е 



• 




^V^ 


ч ^1 
















ть ; 


ir 31 

*J 

5 


L 

U 

С 


с 
É 

<U 

*J 

С 




о 


jours 
> 



с 

V 





60 



SO 
Temps ( jours 



FIG. 2. Dynamique de l'absorption et de la desorption du zinc-65 par les anodontes en fonction 
de la variation de la teneur en zinc-65 de l'eau. 



leur propre niveau de contamination augmente. 

C'est effectivement ce que Ton observe en mesurant régulièrement la teneur en 
zinc-65 des animaux vivants (Fig. 2, Tableau 2). 

En ce qui concerne la contamination nous pouvons observer, compte tenu des écarts 
individuels importants, qu'il est difficile d'obtenir un état d'équilibre et, qu'en tous 
les cas, pour l'atteindre, le temps doit être très long. Il semble même que la dé- 
croissance de l'activité des anodontes après chaque contamination soit moins rapide. 
Ceci confirme les résultats de Keckes obtenus sur Mytilus galloprovincialis qui 
montrent que la perte de zinc dépend du temps d'exposition des animaux au zinc-65 
[11] [12]. Le phénomène le plus général réside dans la rapidité de la fixation du zinc- 
65. Chipman et Col. sur des truites montrent la rapidité des échanges [13]; sur des 
coquilles saint -Jacques, Borough et Col. montrent que deux heures sont suffisantes 
pour atteindre un pic d'activité [14]. L'accumulation de zinc-65 est proportionnelle 
à la concentration de l'eau, ce qui est conforme aux résultats de Pauley et Nakatani 
[15]. 

En plaçant des anodontes dans un circuit d'eau inactive, la perte de zinc semble 
s'effectuer selon une courbe uniforme et correspond à une période biologique de 
l'ordre de 31 jours. D'après Young et Foison, en transportant des moules {Mytilus 
galloprovincialis) d'une zone contaminée vers une zone inactive la baisse de la con- 



112 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLEAU 2. Evolution de l'activité totale des Anodontes en fonction de la variation de la teneur 
en zinc-65 de l'eau. 



Temps 




Acti 


vité des 
( comptage 


In odor, tes 
des anirr; 


en 
aux 


coups/minute 
vivants) 




X* 


-] 


heure 


3 


34 - 


4 


030 - 


3 


640 - 


с: 


58O 


- 4 


490 


\ ■- 


4 250 


6 


heures 


9 


650 - 


10 


8бо - 


7 


61O - 


9 


320 


- 9 


890 


I +* 
I cd 


9 460 


24 


heures 


10 


обо - 


13 


550 - 


10 


140 - 


10 


710 


- 11 


680 


1 ö 

f -H 


11 230 


30 


heures 


9 


450 - 


13 


5бо - 





790 - 


10 


750 


- 12 


110 


E 

cd 


11 130 


2 


jours 


9 


330 - 


12 


250 - 


10 


300 - 


10 


250 


- 11 


150 


с 


10 бсо 


54 


heures 


9 


390 - 


11 


850 - 


10 


880 - 


10 


100 


- 11 


110 




10 5?0 


4 


jours 


8 


290 - 


11 


390 - 


10 


580 - 


9 


65O 


- 10 


860 




10 220 


7 


jours 


7 


98o - 


10 


78o - 


10 


850 - 


9 


58O 


- 13 


620 


1 щ 

и 


10 730 


8 


jours 


7 


280 - 


Q 


950 - 


9 


930 - 


8 


610 


- 13 


320 


1 '* 


10 с • с 


9 jours ( 1h) 


10 


48o - 


13 


490 - 


13 


870 - 


12 


l4c 


- 18 


180 




13 бзо 


9 


( 6h) 


17 


040 - 


19 


650 - 


18 


510 - 


16 


220 


- 21 


350 


\ а 
1 о 


18 550 


10 " 


(36h) 


17 


920 - 


21 


300 - 


20 


4l0 - 


17 


380 


- 23 


730 


1 -н 


20 15O 


11 " 


( 2 j) 


17 


280 - 


21 


54o - 


21 


380 - 


18 


330 


- 25 


260 


/ 1 


20 97с 


14 " 


( 5 j) 


16 


730 - 


23 


001 - 


20 


750 - 


17 


240 


- 24 


080 


•н 


20 78С 


15 " 


( 6 j) 


15 


760 - 


21 


190 - 


20 


490 - 


16 


590 


- 24 


300 


Е 


20 070 


16 


( 7 j) 


15 


580 - 


20 


000 - 


20 


090 - 


16 


640 


- 2J> 


580 


г • 4 - > 


19 5 60 


17 " 


( 3 j) 


15 


140 - 


20 


710 - 


18 


330 - 


16 


150 


- 23 


230 


i о 


19 090 


18 " 


( 9 j) 


13 


890 - 


19 


690 - 


18 


620 - 


15 


830 


- 22 


090 




13 580 


22 " 


(13 j) 


12 


620 - 


- 


160 - 


16 


500 - 


14 


000 


- 19 


760 


s 


16 83с 


25 " 


(16 j) 


13 


110 - 


18 


680 - 


10 


400 - 


13 


800 


- 20 


890 


/ ™ 


17 820 


29 " 


(20 j) 


13 


000 - 


19 


890 - 


16 


110 - 


13 


920 


- 21 


250 > 




17 900 


30 jours ( 1h) 


16 


900 - 


24 


- 


22 


900 - 






- 26 


960 


1 


21 960 


30 ' " 


( 7h) 


23 


030 - 


29 


830 - 


28 


050 - 


23 


620 


- 33 


200 




2? 550 


31 


( 1 j) 


22 


590 - 


29 


З90 - 


27 


410 - 


23 


190 


- 33 


570 


1 £ 


27 330 


32 


( 2 j) 


20 


920 - 


29 


210 - 


26 


030 - 


22 


520 


- 26 


160 


1 ° 


25 230 


35 " 


( 5 j) 


25 


260 - 


28 


990 - 


24 


810 - 


21 


340 


- 32 


020 


ч 


27 0С0 


37 


( 7 j) 


20 


730 - 


30 


1S0 - 


25 


740 - 


21 


720 


- 33 


OSO 


Í 2 


26 800 


39 


( 9 j) 


18 


860 - 


30 


000 - 


24 


520 - 


21 


520 


- 32 


65O 


•й 


26 500 


42 


(12 j) 


19 


160 - 


29 


140 - 


24 


400 - 


20 


87O 


- 31 


770 


> 4-> 


26 100 


45 » 


(15 j) 


18 


640 - 


28 


'+80 - 


22 


840 - 


20 


18O 


- 30 


600 


с 


25 ^00 


ho .. 


(19 j) 


17 


700 - 


27 


460 - 


22 


310 - 


19 


300 


- 29 380 


1 ° 


24 ^00 


52 " 


(21 j) 


17 


780 - 


27 


240 - 


21 


930 - 


19 


740 


- 29 


110 


1 ° 


24 6С0 


56 " 


(25 j) 


16 


720 - 


27 


280 - 


21 


320 - 


17 


770 


- 27 


600 


1 

1 • 


23 800 


57 


(26 j) 


17 


910 - 


27 


120 - 


20 


680 - 


17 


930 


- 27 


540 


г-Л 


24 100 


59 


(28 j) 


17 


1б0 - 


26 


18O - 


20 


540 - 


16 


840 


- 26 


260 




23 250 


60 " 


(29 j) 


17 


- - 


2Ê 


730 - 


21 


040 - 


17 


330 


- 26 


190 




23 сСО 


60 jours ( 6h) 


15 


220 - 


17 


400 - 


14 


000 - 


21 


550 


- 20 


240 




22 600 


61 


' ( 1 j) 


14 


090 - 


15 


690 - 


13 


240 - 


20 


360 


- 20 


170 


) с 


21 700 


63 ' 


' ( 3 j) 


13 


34o - 


лк 


830 - 


12 


370 - 


19 


o4o 


- 17 


96O 


1 -н 


20 100 


66 


' ( 6 j) 


11 


480 - 


12 


560 - 


15 


100 - 


14 


490 






cd 


17 600 


70 


' (10 j) 


10 


370 - 


11 


580 - 


13 


910 - 


13 


070 






> -ri 


i6 зоо 


74 • 


' d 2 » j) 


10 


720 - 


12 


030 - 


14 


370 










cd 


16 500 


76 • 


■ db j) 


9 


590 - 


12 


760 - 


13 


300 










1 ** 
с, 


16 000 


80 


• (20 j) 


9 


040 - 


12 


600 














1 ° 


14 800 


83 ' 


' (23 j) 


8 


740 - 


11 


390 














/ >i) 
' 


13 880 



* Dur:;, celte colonne les résultats sont donnés en tenant corrpte de 
la décroissance physique du zinc-65. 

centration en zinc s'exprime par une exponentielle simple correspondant à une période 
biologique de l'ordre de 76 jours [16]; dans les mêmes conditions avec Crassostrea 
gigas Seymour trouve une période de 300 jours [17]; d'après des informations non pub- 
liées de Price la période ne serait pour Mercenaria mercenaria que de 30 jours [2]; 
par contre, Harvey qui a travaillé sur Lampsilis radiata distingue une période rapide 
voisine de 3,5 jours et une lente de 40 jours [18]. 



FOULQUIER, BOVARD et GRAUBY 



113 



Séd .me n t 



Anodon Les 




2.6% 



Graphique n° 1 Constitution de l'aquarium 
(Poids total с- 87 200g) 



0, 2 % 




6, 2 % 



Graphique n° 2 Ré partition de l'activité à la fin 
de l'expérience 
(Activité totale ^ 6223- 10 5 Des/mm.) 





i "¿rz; 



Coquille 



Parties molles 



= Liquides internes 




10°/. 



Graphique n° 3 

Par ra p port à l'activité 

totale de l'animale 

(Activité moyenne 

~2900 10 3 Des/min ) 



1.5% 





Branchies 


Masse 
I musculai re 




m 


Manteau 


1 Masse 

jj viscera le 




Graphique n°4 

Par ra p port à l'activité 
totale des parties molles 



(Activité moyenne. 

~ 2000 10 3 Des/mm 



GRAPHIQUES 1-4. Distribution du radiozinc dans l'anodonte. 



114 PROC. FOURTH EUROP. MALAC. CONGR. 





Teneur 


en zinc 65 








__^^_____^^____^^^___^ 




(en Des/min /cc ) 












Échelle 


logarithmique 










10.000 






















































5000 




























' 


1 

\ 












1000 


L_ 












• 












500 


\ 














\ 




^ 


к • 










SO 
















\ 




















• 
















• 


40 




' 1 


J 


1 1 


1 


1 



10 20 30 40 50 6O 70 

Temp* (jours ) 

FIG. 3. Evolution de l'activité de l'eau. 

Nous retiendrons essentiellement de cette expérience que la fixation du zinc-65 
par les anodontes est intense et rapide puisqu'on obtient un pic d'activité dès le 3ème 
à 4ème jour, cette fixation est d'autant plus importante que l'activité de l'eau est 
élevée. La perte de zinc est un processus relativement long qui, pour être saisi dans 
toute sa complexité, devra être complété par Г étude la la période biologique de chaque 
organe. 

ETUDE QUANTITATIVE DE LA FIXATION DU ZINC-65 PAR LES ANODONTES ET DE 
SA REPARTITION 

Dans un aquarium contenant 70 litres d'eau et 15kg de vase, on place 18 anodontes 
(graphique 1). On contamine l'eau de l'aquarium à 4 ^Ci/litre, soit une activité 
totale de 6223.10 5 des/min. L'expérience dure 59 jours. Il est intéressant de voir 
dès maintenant comment se répartit le zinc-65 en fin d'expérience dans les différents 
constituants de l'aquarium (graphique 2). L'activité des anodontes représente environ 



FOULQUIER, BOVARD et GRAUBY 
TABLEAU 3. Evolution de l'activité de l'eau. 



115 



Temps 


activité de l'eau 


(Des/min/cc ) 


Instant de la 


8 890 


contamination 




^ heures 


3 3^0 


1 jour 


1 ^0 


2 jours 


790 


3 


280 


k 


2k0 


7 " 


130 


8 » 


110 


9 


100 


11 » 


80 


14 » 


50 


16 " 


*K> 


21 " 


30 


23 " 


25 


35 » 


20 


k2 " 


20 


59 


30 


72 " 


15 



38 400. 10 3 des/min. Ainsi, la majeure partie du zinc-65 a été retune par le sédiment. 

1. Evolution de l'activité de l'eau 

Le Tableau 3 et la Fig. 3 montrent la décroissance très rapide de l'eau qui tend vers 
un état d'équilibre. A la fin de Г expérience nous avons effectué plusieurs prélèvements 
de vase qui nous ont donné les résultats suivants, en des/min/g frais: 17 400; 18 000; 
26 800; 16 000; 24 200; 26 700; 12 500; 23 500; 16 600; 21 000. L'activité totale du sédiment 
est d'environ 583. 10 6 des/min. La distribution du zinc dans le sédiment n'est homo- 
gène ni en surface ni en profondeur. 

Ces résultats correspondent à ceux trouvés par Rowe & Gloyna [19]. Remarquons 
qu'une partie du zinc reste en solution et qu'une autre peut se fixer sur tous les fins 
matériaux en suspension. En plus des mécanismes d'échanges ioniques entre l'eau 
et le sédiment, il se produit de simples phénomènes d' adsorption. 

2. Teneur en zinc-65 de l'animal total, de la coquille, des tissus mous et des liquides 
internes 

a) Evolution des activités spécifiques 

Les Fig. 4 et le Tableu 4 montrent la très grande variabilité des résultats que l'on 
obtient d'un échantillon à l'autre. Ces écarts individuels sont de l'ordre de 1 à 4. Le 
résultat principal réside cependant dans le fait que la coquille et les tissus mous 
fixent très rapidement le zinc et que cette fixation se maintient par la suite à l'in- 
térieur de certaines limites (Fig. 4Bet4C). L'activité spécifique des liquides internes 
décroît en fonction de la baisse de celle de l'eau mais lui demeure toujours supérieure 
(Fig. 4D). 

Au niveau de la coquille la fixation du zinc-65 est due essentiellement à des méca- 
nismes d'adsorption [3] [6] [7] [12]. Par contre les tissus mous présentent une grande 
affinité pour le zinc et ce sont des phénomènes métaboliques qui dominent [15] [18]. 



116 



PROC. FOURTH EUROP. MALAC. CONGR. 





Des / mi 


n /g Frais (a) 


Ech.i 


« TO^i-Ubmiqu« 




• 
















± L i 






! 




1 — 


_i 


4- 




4 


« 




i 




L * * : 










A 






t 




__ = L_ 


J * .- 


*i 


5000- 
1000 


Animal Lolai 












1 


1 



in/cc (5) 



4 



V 



Liquides internes 



10 20 30 ¿.0 SO 60 10 20 30 АО 50 60 

Temps 
(Jours) 



Des/mm/g frais В tcntiu io9«riinm^û« « Des / mm /g frais (с) 





















5 


* 










- 




; 







Pa 


« 
rties г 


noites 


















1000 

















Coquilles 



10 20 30 40 50 60 10 20 30 *0 50 60 

Temps 
I Joursl 

FIG. 4. Teneur en zinc-65 de l'animal, des liquides internes, des parties molles et de la co- 
quille en fonction du temps. 



FOULQUIER, BOVARD et GRAUBY 



117 



TABLEAU 4. Evolution de l'activité spécifique de l'animal total, de la coquille, des parties 
molles et des liquides internes en fonction du temps. 



Temps 






Activi 


.tés spécifiques (Des/min 


g frais ou ce) 






1 j 


Animal 


total 


Coquille 


Partiee 


molles 


Liq\ 


lides 


in 


ternes 


10 


000 - 


12 150 


6 570 - 6 87O 


14 690 


- 19 400 


7 


100 - 


7 


470 


* 3 


9 


290 - 


13 770 


5 200 - 7 180 


24 370 


- 26 ¿+00 


1 


65O - 


6 


120 


? j 


30 


000 - 


31 200 


7 970 - 6 000 


85 500 


- 80 890 


5 


400 - 


3 


900 


1* d 


11 


600 - 


24 290 


3 69O - 7 070 


29 340 


- 67 600 


1 


200 - 


k 


490 


21 j 


10 


600 - 


11 660 


2 420 - 3 310 


22 130 


-25 100 


1 


480 - 


1 


790 


35 j 


12 


450 - 


11 0¿t0 


4 090 - 2 590 


34 570 


- 33 500 




280 - 




38О 


^2 j 


8 


790 - 


15 090 


6 89O - 2 26O 


25 620 


- 46 500 




221 - 




400 


59 j 


26 
28 


200 - 
700 - 


7 640 
29 390 


3 670 - 5 170 
7 56O - 1 790 


120 000 
88 100 


- 19 300 
-100 800 


1 


480 - 

180 - 


1 


400 

310 



TABLEAU 5. Distribution du zinc-65 dans l'organisme en fonction de l'activité totale de l'animal. 



Temps 


Pourcentage de zinc-65 contenu dans chaque organe 
en fonction de l'activité totale de l'animal 


Coquille 1 


Parties molles 


Liquides 


internes 


1 jour 


16 - 17,5 


59 - 65 


гз - 


17,5 


4 jours 


17 - 14 


76 - 70 


7 - 


16 


7 jours 


6-4 


85 - 90 


8 - 


6 


14 jours 


9 - 8 


87 - 84 


4 - 


8 


21 jours 


6 - 6,5 


90 - 88 


4 - 


5,5 


35 jours 


9-7 


90 - 91,5 


1 - 


1,5 


42 jours 


27-5 


72 - 94 


1 - 


1 


59 jours 


4 - 19,5- 6 - 1,5 


95-78,5-92-96,5 


1 - 2 - 


2-2 



b) Distribution du radiozinc 

Le graphique 3 et le Tableau 5 montrent qu'en fin d'expérience la majeure partie 
du zinc-65 se trouve dans les tissus mous. Selon la composition physico-chimique 
de Геаи, l'espèce, et les conditions expérimentales les phénomènes d'adsorption 
peuvent être plus ou moins intenses. Parfois la coquille peut retenir plus de 60% du 
zinc-65. Ce peut être le cas, par exemple, lorsque l'expérience est poursuivie dans 
un milieu ne contenant pas de sédiment; dans ce cas, en effet, la surface de la coquiUe 
offerte à l'adsorption est beaucoup plus importante. 



118 PROC. FOURTH EUROP. MALAC. CONGR. 

Dans cette question de la distribution du zinc-65 dans l'organisme, plusieurs auteurs 
ont montré, sur des bivalves marins, toute l'importance de la teneur en zinc-stable 
[8] [10] [13] [20] [21] [22]. Différentes analyses permettent de montrer que, pour les 
parties molles, le zinc-65 suit le métabolisme du zinc stable [15] [23] 2 . La distri- 
bution du zinc-65 correspond à celle du zinc stable. 

3. Teneur en zinc-65 des principaux organes internes 

a) Evolution des activités spécifiques 

Lors de chaque prélèvement d' anodontes nous avons disséqué les principaux organes 
internes et mesuré leurs activités spécifiques respectives (Tableau 6). Malgré les 
écarts individuels, on constate une fixation rapide du zinc-65 qui atteint un maximum 
d'activité dès le 7ème jour puis se maintient par la suite. Si on considère les acti- 
vités spécifiques décroissantes des organes, à partir du moment où l'eau est à rééqui- 
libre", c'est-à-dire au 35ème jour, elles se classent de la manière suivante: 

- Branchies (avec des valeurs supérieures pour les branchies internes) 

- Siphons 

- Palpes 

- Bord du manteau (le reste du manteau ayant une activité nettement plus faible) 

- Masse viscérale 

- Masse musculaire 

Ainsi les organes intervenant dans le transfert des particules et dans la filtration 
de l'eau ont des teneurs en zinc-65 particulièrement fortes de même que le bord du 
manteau. Ces résultats concordent avec ceux trouvés sur des mollusques marins et, 
en particulier, avec les expériences conduites par Pauley et Nakatani [7] [12] [13] [15] 
[22]. Notons, par ailleurs, que le sang (ou hémolymphe) a une activité spécifique 
élevée et toujours nettement supérieure à celle du liquide extrapalléal. (Certaines 
mesures donnent également des teneurs en zinc-65 élevées pour le coeur). 

On peut donc conclure que la filtration de l'eau, les échanges osmotiques et certains 
processus métaboliques au niveau intestinal et au niveau du manteau jouent un rôle 
particulièrement important dans la fixation du zinc. Les siphons et les palpes inter- 
viennent dans la collecte des particules en suspension qui passent ensuite dans le 
tractus digestif, le sang transporte ensuite le zinc vers les epitheliums des branchies 
et du manteau. Au niveau des branchies il doit se produire également des phénomènes 
d'adsorption par le mucus qui les recouvre. Pour ce qui est du manteau Istin a montré 
le rôle de l'anhydrase carbonique localisée à la périphérie; or cette enzyme contient 
du zinc [24]. D'autres enzymes d'ailleurs renferment du zinc. 

b) Distribution du radiozinc 

Si on ne considère que l'activité totale des tissus mous, la distribution du zinc 
s'effectue conformément aux résultats donnés dans le tableau 7 et le graphique 4. Ces 
résultats correspondent à la teneur en zinc stable des différents organes [15]. 

4. Les facteurs de concentration 

Ils représentent la valeur du rapport, à l'équilibre, entre l'activité spécifique de 
l'animal ou de ses organes avec celle de l'eau. C'est une donnée particulièrement 
importante dans le domaine de la protection sanitaire car elle exprime la capacité de 
fixation des radioéléments par une espèce. 



2 SurUnio la distribution du zinc stable est de 0,25 à 0,79% du poids sec dans les tissus mous et 
de 0,001 à 0,018 dans la coquille. 



FOULQUIER, BOVARD et GRAUBY 119 

TABLEAU 6. Activités spécifiques des organes internes en fonction du temps (Des/min/g frais). 



Q) 


о 


о 


О 


о 


о 


о 


о 


о 


О 


о 


о 


о 


о 


о 


о 


a 


оо 


СО 


ЧО 


оо 


о 


о 


о 


о 


о 


о 


о 


о 


о 


о 


о 


с 


1Л 


-d- 


со 


ON 


иЛ 


-d- 


4D 


"d" 


г " 


мл 


ОЛ 


Г>- 


о- 


СО 


00 


>-> 










00 


CN 


ОО 


ON 


ОО 


о 


ко 


-d- 


ГЛ 


с^ 


40 


о 










-d- 


ON 


т- 


мл 


ил 


МЛ 


ил 


-d- 


мл 


-d- 


J- 


s 










*"" 
























о о 


О О 


о о 


о о 


о о 


О О 


о о 


о о 


о о 


о о 


о о 


о о 


о о 


о о 


о о 




О ч~ 


СО МЛ 


мл ГО 


V- иЛ 


о о 


ОО о 


ил о 


оо ил 


ON МЛ 


оо О 


О чо 


V- 00 


чО О 


ОЛ о 


-d- Г^ 




-3" МЛ 


т- ол 


V- О 


СО ОЛ 


со мл 


СО чО 


О со 


40 С-- 


о о 


ON CN 


ЧО -d- 


J 


0О иЛ 


ил С 4 ^ 


мл ч- 




,_ 


^_ 


<- 


,- 


ОО МЛ 


-d" чО 


г^ <~ 


О -d- 


О- о 


r>.-d- 


х> о 


ОЛ ОЛ 


•О СЛ 


О мл 


«- ол 












ил О- 


О- СО 


-d- ОЛ 


^- 40 


í-oo 


-с 


ОЛ ОЛ 


00 СО 


гл- 


<- CN- 


-з- ил 












ОЛ 


МЛ 


00 


















ол 


1 1 

О о 


о о 


о о 


о о 


о о 


о о 


О О 


о о 


о о 


о о 


о о 


о о 


о о 


CO о 


о о 




ОО ON 


CO t>- 


40 ил 


ил со 


о о 


о о 


CO чо 


ON 00 


ОЛ мл 


О со 


мл О 


00 00 


□О ГЛ 


ON CN- 


СЛ о 




-d- ï- 


МЛ LTN. 


МЛ 


СО КО 


ил о 


-d- CO 


ил МЛ 


V- 00 


мл оо 


Э 


МЛ о 


ол ол 


►d" -з" 


-3- ON 


СЛ CN- 




^_ 


^_ 




<_ 


МЛ СО 


г- иЛ 


г- ОЛ 


О -d- 


-d" On 


О СО 


оо -d- 


О- О- 


00 СО 


ил -d" 


ол мл 












ч— V— 


О- "Л 


О ко 


СЛ ил 


ОО CN- 


О- 00 


г^ ил 


чО ON 


¡S\KO 


00 СО 


ЦЛ40 












МЛ г- 


-J- МЛ 


ОО 




^~ 
















О о 


о ил 


ил О 


о о 


о о 


О о 


о о 


о о 


о о 


о о 


о о 


о о 


о о 


о о 


о о 




AJ О 


ОЛ ОЛ 


-d- ОЛ 


[>- ОЛ 


-d- О 


СО О 


мл о 


МЛ 40 


мл ол 


00 -d" 


V-40 


>ил о- 


О чо 


МЛ ON 


-d- О- 




AJ J- 






МЛ 40 


О -d- 


40 О 


С^чд 


о -d- 


00 мл 


КО иЛ 


ко -d- 


ОЛ г- 


-d- О 


ЧО 40 


оо -d- 


r\J 
-3" 










ГО ON 


МЛ О 


CN0O 


40 мл 


мл -d- 


КО оо 


J- -d- 


МЛ ОЛ 


ON-d- 


О- МЛ 


т- UN 












-d" ил 


-d- чо 


МЛ ^л 


t- J- 


V- с^ 


г- МЛ 


00 -d- 


г- 00 


00 


ОО МЛ 


МЛ 4D 




О О 


ил о 


О О 


о о 


О о 


О О 


о о 


о о 


о о 


о с 


о о 


о о 


о о 


о о 


о о 




со ОО 


о о- 


КО мл 


-d- о- 


ОЛ CKI 


О о 


О чз 


ил40 


-т со 


0Л иЛ 


-d- чо 


X) МЛ 


иЛ О 


t>- г>- 


о о 




СЛ мл 




СО 


-d- ил 


-d- ил 


-d- со 


-d- ^г 


-d- ON 


On г>- 


МЛ МЛ 


:-Л ил 


^г оо 


олчо 


г_ ^~ 


1Л-СО 


1Л 

ГЛ 










5- мл 


со -d- 


ко мл 


оо ол 


V- чо 


-d- г- 


ГЛ^ Г>_ 


-d- -d- 


CNCO 


ил N- 


СО МЛ 












ск\ ил 


г- мэ 


ОО -d- 


оо <- 




ол *~ 




N- 00 




00 -d- 


ОО ГЛ 




О ил 


о о 


о о 


о о 


О О 


О о 


О О 


о о 


О О 




о о 


о о 


о о 


о о 


о о 




СО ОЛ 


со со 


-d- мл 


ОЛ ко 


О О 


О оо 


О ON 


г- -d" 


ил Cn 




■•л оо 


•л о 


ч- ил 




-d- О 




J- о- 


ил со 


ОО О 


ON ил 


иЛ ОЛ 


On on 


LT\ CN 


ил V 


т- МЛ 


оо --•- 


!>■ ОЛ 


О J- 


оо мл 


-d- "г- 


О [N- 


(\J 


^_ ^_ 






СЛ мл 


СЛЧО 


МЛ О 


00 1> 


-d- О- 


мл О- 


V- г- 


<- ON 


МЛ мл 


' 


сл СО 


О -з- 












МЛ МЛ 


ил ил 


МЛ 00 


«- 00 


оо мл 


■- 00 


N -Л ил 


ОЛ ГЛ 


V- f. J 




V- МЛ 




о о 


о о 


О О 


о о 


О о 


О О 


О О 


о о 


О О 


о о 


о о 


о о 


о о 


о о 


о о 




V- On 


CN- ил 


-d- О- 


О -d- 


о_ г^л 


-d- О 


40 С^ 


ГО 00 


О о- 


О CN- 


о о 


X) Г>- 




ГЛ О 


О ос 




ол -d- 


ил ил 


C^-d- 


СО Г>- 


ил Ск1 


ОО ON 


-d" чо 


40 On 


Г>- т- 


ЛЛ CN 


ON иЛ 


Х> -3- 


О г- 


Í 


-d- V- 


-d~ 


Т--3" 


-d~ 




г- иЛ 


-d- -d- 


*- МЛ 


СЛ On 


-d" г- 


CN О 


о-, г: 


» о- 


^Л Г>- 


МЛ V- 


СЛ ^о 














ЧО ОО 


ÎN С\! 


ил ил 


00 ил 


ол ил 


т— - — 


■d- on 


00 U"N 


iAJ иЛ 


оо ил 


оэ ил 












*~ 


ОЛ 






















о о 


О о 


о О 


о о 


о о 


О О 


о о 


О О 


о о 




о о 


о о 


о о 


о о 


о о 




О мл 


О ГЧ] 


-d- г- 


го -d- 


О -з" 


О О 


О L^- 


Г>-СО 


О чс 


0N -CT 


О СО 




о о 


0N 40 






-d- On 


ОЛ О 


мЛ О 


О ОЛ 


О í- 


ко -d- 


т- О 


-d- О 


СО со 


О -d- 


иЛСО 


г>. г- 




ГЛ О 


V- ' 


t ^ - 


ИЛ МЛ 


lA-d" 


-d- г- 


0--3- 


ON ОО 


oj мл 


мл *- 


мл ил 


со о 




J- о 




•Л гЛ 


г- ОО 














О CKi 




CN О- 


'О ил 


ил -d- 


ил -d- 


О г>- 


-з- ГЛ 


-d- г-л 


СГЧ СО 


L0\ ОО 












*~ *~~ 


го оо 






















о о 


О О 


О О 


о о 


о о 


О О 


о о 


о о 


о о 


о о 


о о 


о с 


о о 


о о 


о о 




ил оо 


КО со 


со мл 


ОО о 


О- о 


О ко 


О гЛ 


оо ил 


о о 




Х> ЧО 


го ил 


АЛ -d' 








40 с- 




ОЛ МЛ 


иЛ СО 


ГЛ ON 


ОЛ ON 


С^чО 


-d- Г>- 


*" г_ 




-NOO 


Ï- МЛ 


ON CO 






-d- 


г- 40 




иЛ 


-d" ON 


ОО CN- 


-d- -d- 


МЛ 00 


т- г- 


^ ^г 


г- С 


ОО МЛ 


_Л ON 


иЛчО 


г- Г>- 


я— [>- 












ил ил 


ко ил 


-d- чо 














л; i\j 


ил иЛ 




О о 


о о 


о о 


О О 


о о 


О О 


О О 


о о 


о о 


э с 


о о 


о о 


о с 


о о 
о о 

ЭО ГЛ 


о о 

о с 
1 




о о- 


со ил 

О- СЛ 


LT\4D 

г- О 


О О 


-d- СЛ 

ко О- 


О ОО 
СЛ V- 


О со 

МЛ ил 


ил О 
мл -d" 


ил о 

Г>- 40 


3- оо 


•■л о 

О ON 


г>- о 
■ 


V- О 

о о 


5_ 


О- г ^- 


со 


с 4 - гл- 


s— *— 


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ЬЛ мл 


г- CN 


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ON ON 


■о ил 


vO ил 


чО мл 


ГЛ 'Л 


О 40 


СО On 

МЛ^- 










" 


г- МЛ 


мл мл 


*- OJ 








г- МЛ 








to 




1-1 




























и 

3 




d 
•о 








Ю 


И 












со 

и 






о 


И 


H 






W 


О 


0) 


















1) 


1—1 






ф 


с 


с 






3 




о 


3 








й 


d 


l—i 






и 


и 




3 


d 




(ч 


о 


си 






и 


р< 


d 




с' 


о 


<L> 




d 


о 




■н 


4-> 


I—Í 
d 
и 

о 

W 




to , 


со 


d 


*03 




-р 


4-> 




H 


ID 






г' 


о 




О) / 


•н 


и 

о 


1-1 

ta 




о 
to 


ю 


И 


d 
+-> 
о 


с 

G 


Й 




о 
til 








со 








о 


о 


о 






3 




3 








/со 

/ ° 
/ й 


■И 


а> 


о 

тЗ 

•н 

3 
СГ 

■н 


"ьо 

с 


W 


■н 

о 


•н 
о 


•н 

о 
с 


3 
cd 

о 
-р 


ТЗ 

■а 


ТЗ 

о 


а 
с 
о 


Г: 

И 
4) i-I 
И г 


И 

о 

H 


> 
4) 

ta 


И 

р 


а* 


Er 


г 
Í-1 


и 


г; 
и 


с 
d 


о 


и 
о 


а, 

■И 


' - • 
d о 


to 


И 


1—! 

г 


о 


J 


>J 


►3 




СО 


Й 


РЗ 


""' 






W 











120 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLEAU 7. Distribution du zinc-65 dans les organes en fonction de l'activité totale des tissus 
mous. 



Temps 


Pourcentage de zinc-65 contenu dans chaque organe 
en fonction de l'activité totale des tissus mous 


35 jours 


Branchies 
et palpes 


Manteau 


Masse musculaire 


Masse viscérale 


42 - 22 - 


16 - 9 - 


if - 10 - 


38 - 59 - 


42 jours 


26 - 33 - 


16 - 18 - 


6 - 9 - 


52 - 40 - 


59 jours 


44 - 45 - 
37 - 35 - 


16 - 13 - 

15 - 14 - 


8 - 16 - 
14 - 15 - 


32 - 26 - 
34 - 3 1 * - 


Moyenne 


35 


15 10 


40 



Nous avons porté les principaux résultats dans le tableau 8 ils ne font d'ailleurs 
que confirmer la capacité de fixation plus ou moins grande d'un organe pour le zinc. 
Notons simplement que les valeurs obtenues sont particulièrement fortes, et supérieures 
à celles des bivalves marins, mais restent, comme en milieux marins, nettement 
inférieures à celles correspondant au facteur de concentration du zinc stable. 

Pour le zinc stable les moules ou les huitres peuvent avoir des facteurs de concen- 
tration de l'ordre de plusieurs milliers; 14 600 pour Crassostrea gigas, 17 000 pour 
Pectén japonicus, 40 000 pour Ostrea edulis [7] [17] [20]. Pour Lampsilis sp., Harvey 
donne un facteur de concentration pour les tissus mous voison de 4100 [18]. Si les 
anodontes contiennent entre 0,2 et 0,4 mg/g de zinc et l'eau douce environ lO^g/litre, 
le facteur de concentration pour le zinc stable se situe entre 12 000 et 24 000. 

CONCLUSION 



Ces premiers résultats nous donnent des informations dans trois domaines différ- 
ents et nécessitent pour chacun d'eux des approfondissements. 

Sur le plan sanitaire , nous avons pu observer une fixation rapide et importante du 
zinc-65 par les anodontes qui est fonction de la teneur en zinc-65 de l'eau. La période 
biologique relativement longue est voisine de 31 jours. H faut cependant noter que, 
compte tenu de la très forte capacité de rétention du zinc par le sédiment, la quantité 
restant disponible pour une contamination éventuelle des organismes est faible. Le 
Facteur de Concentration de l'anodonte est voisin de 950 mais peut dépasser 7 000 
pour les branchies. La capacité de filtration de l'eau permet à ces bivalves d'atteindre 
rapidement un pic d'activité [8]. H semble d'ailleurs que la quantité de zinc-65 
absorbée soit en relation directe avec le volume d'eau filtrée [25]. Les bivalves, et 
les anodontes en particulier, peuvent servir d'indicateurs de la présence de zinc-65 
dans l'eau et contribuer à l'établissement des concentrations maximales admissibles 
[10]. 

Sur le plan physiologique , le zinc-65 peut servir d'indicateur pour suivre le métabo- 
lisme du zinc. Nous avons vu que des organes jouent un rôle particulier dans ce 
domaine. Des mécanismes d'échanges et d'adsorption s'établissent au niveau des 
branchies; les siphons et les palpes interviennent dans la collecte des particules; 
l'hémolymphe joue le rôle de transporteur du zinc vers les epitheliums du manteau. 
Ces études sont à poursuivre en utilisant, en particulier, les méthodes autoradio- 
graphiques. 

Sur le plan biologique et écologique , les questions essentielles résident dans la voie 
d'entrée du zinc et dans le rôle des facteurs du milieu. En effet, le zinc soluble peut 



FOULQUIER, BOVARD et GRAUBY 



121 



TABLEAU 8. Facteurs de concentration du zinc-65 de I'Anodonte et de ses différents organes 
en fonction du poids frais. 



<1> U 
Ш О 

tí и 

S -H 

> 


ГА 


vD 
см 


а 


о- 


ON 

J- 


CO 
CO 

LA 


О 
•M 




1 

i о 
1 °^ 

VO 
CM 


¡0 • 
О -P 
гЧ о 
О tí 
СО ТЗ 

tí -ö 
S ni 


SA 

CM 
LA 


ON 


ил 
cn 


г А 


LA 
ON 

CM 


ÍA 


О 

ОЭ 
ГА 




LA 
LA 
СО 


muscul . 


CM 
О 


LA 

OJ 


ГА 


о 
см 
vO 


■■ 

IA 


ГА 

CM 


О 

LA 


CN 


О 

[>- 

CM 


и 

G 

о 
p, 

■H 

w 


ГА 
CM 
ON 


CVJ 


LA 
СЛ 
СМ 


ON 

vo 

CM 


CA 


CO 

OO 

LTN 


LA 

VO 
LA 

СО 


LA 

j 

LA 


о 

ГА 


(tí 

о о 
-p -p 
u tí 

<L> Си 
К E 


ГА 
СО 

CM 


Lf\ 


СО 


см 


CO 

ГА 


О 

-3" 


о 

VO 


CM 


LA 

1 ^ 

i v " 


P 3 

a> 
ТЗ цр 

^ tí 

О Cu 
« E 


со 
CM 

vG 


СО 
СО 


'О 
Cn 
О 


CM 
ГА 


VO 

о 
on 

VO 


ON 


о 


VO 


S О 

! Ш 
1 с 


re м 

<t> ci 

-p -p 
tí о 

Сб -P 

s: 


СО 


OD 


LA 

1>- 

СО 


CM 


о 
о 

'_'■ 


О 

LA 


LA 

о 


LT\ 

•'A 


i 

о 

СМ 


со 

о 
a 

гЧ 

о 
a, 


VD 
О 
1Л 


с^ 


VO 
V0 


L>- 

vo 

FA 


ON 

с 

CM 


VO 
ON 

CM 

fvl 


ГА 


со 

CN 

: 
i 


О 
LA 

СМ 


га 

О 10 
•H G 
.tí гЧ 

о tí 

С -Р 
со о 

га 


о 

CN 
ГА 

О 


СО 

СМ 


СМ 

." J 

СМ 


LA 

LA 
CO 

CO 


Cvi 

in 


CM 


VO 
VO 


LA 


о 


Ö 


ГА 
см 


о 
га 


On 


CO 

rA 


r^ 


s> 


ГА 

CA 


CD 
G 


о 


и и 
о о 

'О с 

■Н tí 

tí о 

О 4 -Р 

•н с 
^ -н 


LA 


о 
cu 


СМ 


CM 
CM 


VD 
CM 

VG 
VO 


CM 
CM 

CM 

L-N- 

o 


■ 


CM 

О 

О 

LA 


О 


со 

tí со 
W tí 
СО о 
•H Е 
Еч 


CN 
СО 


о 


СО 
ГА 


la 

CO 

LA 

CM 


СО 


О 
СМ 
СМ 

ГА 


о 

гЧ 
■И 

tí 
о' 
о 
о 


LA 

СМ 




СМ 


VO 


О 
CM 


CO 

CM 


о 

CM 


О 


О 
ГА 

см 


гЧ 

Г. H 

Е tí 
■H -P 

tí о 

-< -P 


VO 


о 

СО 

LA 


СМ 


CO 

rA 
CO 


CM 






LA 
LA 
ON 


со , 

s / 

tí /га 

u/ а 

(h/ E 
O/ <U 

' Ен 


'Л 


■о 

СМ 
-3" 


ON 
LA 


О 
tí 

С 

í> 

>5 

О 



122 PROC. FOURTH EUROP. MALAC. CONGR. 

pénétrer par simple échange entre l'eau et l'organisme; lorsqu'il est adsorbe il 
peut être ingéré par l'intermédiaire des particules organiques ou minérales. Par 
ailleurs, des facteurs du milieu tels la turbidité, la température ou la composition 
chimique de l'eau peuvent, en variant, modifier la capacité de fixation des organismes. 
Des protocoles expérimentaux bien appropriés doivent permettre de répondre à 
ces questions. 

BIBLIOGRAPHIE 

BOVARD, P., FOULQUIER, L. & GRAUBY, A., 1969, Etude de la cinétique et 
de la répartition du radiocésium chez un bivalve d'eau douce (Unio requieni 
Michaud). Malacologia, 9(1): 65-72. 

RICE, T. R., 1963, Review of zinc in ecology. Proc. first natn. Symp. on Radio- 
ecology, held at Colorado State Univ., Fort Collins, Colorado, U.S.A., 10-15 
September 1961. Ed. V. Schultz & A. W. Klement, Reinhold Publ. Corp., New 
York, p 617-631. 

GONG, J. K., SHIPMAN, W. H., WEISS, H. V. & COHN, S. H., 1957, Uptake of 
fission products and neutron induced radioculides by the clam. Proc. Soc. 
exp. Biol. Med., 95(3): 451-454. 

SEYMOUR, H. A. & LEWIS, G. В., 1964, Radionuclides of Columbia river origin 
in marine organisms sediments and water collected from the coastal and off- 
shore waters of Washington and Oregon 1961-63. U.W.F.L. 86 Health and 
Safety, 73 p. 

TEMPLETON, W. L. & PRESTON, A., 1966, Transport and distribution of radio- 
active effluents in coastal and estuarine waters of the United Kingdom. In: 
Disposal of Radioactive Wastes into Seas, Oceans and Surface Water. Vienna, 
p 267-289. 

FONTAINE, Y., 1960, La contamination radioactive des milieux et des organismes 
aquatiques, Rapport CE. A., Doc. C.E.N. Saclay, B.P. no 2, France, No. 1588, 
155 p. 

POLKARPOV, G. G., 1966, Concentration of radionuclides of the second group of 
elements in the periodic system. In: Radioecology of Aquatic Organisms, 
North-Holland Publishing Co. Amsterdam, p 81-109. 

POMEROY, L. R., ODUM, E. P., JOHANNES, R. E. & ROFFMAN, В., 1966, Flux 
of 32-P and 65-Zn in a salt marsh ecosystem. In: Disposal of Radioactive 
Wastes into Seas, Oceans and Surface Water. Vienna, p 177-186. 

A.E.C. Research, June 1967, Evaluation of radiological conditions in the vicinity 
of Handford for 1966. B.N.W.L., 439: 14-15. 
10] PRESTON, A., 1967, The concentration of 65-Zn in the flesh of oysters related to 
the discharge of cooling pond effluent from the C.E.G.B. Nuclear Power Station 
at Bladwell-on-Sea. In: Radioecological Concentration Processes, Intern. 
Symp., 25-29 April 1966, Stockholm, p 995-1004. 
Li KECKES, S., OZRETIC, В. & KRAJNOVIC, M., 1968, Loss of 65-Zn in the mussel 

Mytilus galloprovincialis. Malacologia, 7(1): 1-6. 
il Anonyme, Juillet 1964-Juin 1965, Uptake and loss of 65-Zn in mussels in the 
presence of E.D.T.A., Annual Report on Research Contract no. 201/Rl/Rb, 
Institute Ruder Boskovic, Laboratory of Marine Radiobiology, Rovinj and 
Zagreb, Yougoslavie, p 66-77. 
13] CHIPMAN, W. A., RICE, T. R. & PRICE, T. J., 1958, Uptake and accumulation of 
radioactive zinc by marine plankton fish and shellfish. Fishery Bull. Fish. 
Wildl. Serv. U.S., 48: 279-291. 
141 BOROUGH, H., CHIPMAN, W. A. & RICE, T. R., 1957, Laboratory experiments on 



FOULQUIER, BOVARD et GRAUBY 123 

the uptake accumulation and loss of radionuclides by marine organisms. In: 

The Effects of Atomic Radiation on Oceanography and Fisheries. Natn. 

Research Council, Washington D.C., Publ. 551, p 80-87. 
[15] PAULEY, G. B. & NAKATANI, R. E., 1968, Metabolism of the radioisotope Zn-65 

in the freshwater mussel Anodonta californiens is . J. Fish. Res. Bd. Can., 

25(12): 2691-2694. 
[16] YOUNG, D. R. & FOLSOM, T. R., Octobre 1967, Loss of Zn-65 from the California 

sea-mussel Mytilus calif ornianus . Biol. Bull., 133(2): 438-447. 
[17] SEYMOUR, A. H., 1966, Accumulation and loss of zinc-65 by oysters in a natural 

environment. In: Disposal of Radioactive Wastes into Seas, Oceans and Sur- 
face Waters. Vienne, p 605-620. 
[18] HARVEY, R. S., 1969, Uptake and loss of radionuclides by the freshwater clam 

Lampsilis radiata (Gmel). Health Physics, 17: 149-154. 
[19] ROWE, D. R. & GLOYNA, E. F., 1er Sept. 1964, Radioactivity transport in water 

- The transport of Zn-65 in an aqueous environment. U.S. Atomic Energy 

Commission Contract AT(ll-l)-490, 101 p. 
[20] ICHIKAWA, R., 1961, On the concentration factor s of some important radionuclides 

in the marine food organisms. Bull. Jap. Soc. sei. Fish., 27(1): 66-74. 
[21] HIYAMA, Y. & SHIMIZU, M., 1964, On the concentration factors of radioactive 

Cs, Sr, Cd, Zn and Ce in marine organisms. Rec. Oceanogr. Wks. Japan, 

7(2): 43-77. 
[22] КАМЕ DA, K., SHIMIZU, M & HIYAMA, Y., 1968, On the uptake of 65 -Zn and the 

concentration factor on zinc in marine organisms. J. Radiation Res., 9(2): 

50-62. 
[23] GIRADI, F. & MERLINI, M., 1963, Studies on the distribution of trace elements in 

a mollusk from a freshwater environment by activation analysis. EUR-474e. 

Symp. on Radioactivation Analysis and its Application to the Biological Science, 

26-28 Sept., Saclay, France, 26 p. 
[24] ISTIN, M., Janvier 1970, Rôle du manteau dans le métabolisme du calcium chez les 

lamellibranches. C.E.A. -B.I.S.T., 144: 53-80. 
[25] DUKE, T. W., Avril 1967, Possible route of zinc-65 from an experimental estu- 

arine environment to man. J. Water Polit. Control Fed., 39: 536-542. 

SUMMARY 
RESULTS OF EXPERIMENTS ON ZINC-65 FIXATION BY ANODONTA CYGNEA (L.) 

Zinc-65 is an induced radioactive substance found mainly in the waste products of 
nuclear reactors; it is accumulated in highly concentrated form by living organisms, 
molluscs in particular. The development of nuclear plants along the Rhone has led 
the authors to study Zinc-65 fixation (in chloride form) by Anodonta cygnea. 

Two experiments are described: The 1st concerns the dynamic study, by means of 
radioactive measuring of the living shellfish, of Zinc-65 absorption and desorption by 
anodontae, in terms of the varying Zinc-65 content of the water. Zinc-65 fixation by 
these bivalves appears proportional to the Zinc-65 content of the water, and is a rapid 
phenomenon: a maximum activity peak is obtained on the 3rd or 4th day following 
contamination. In an inactive water circuit, the anodontae lose the zinc relatively 
slowly, and the biological period is about 31 days. 

The 2nd experiment is a study of Zinc-65 fixation by the various organs of the 
anodonta after contaminating the water in an aquarium containing sediment. The 
activity of the water is seen to decrease very rapidly, whereas the activity of the 
sediment increases. After 59 days, the water contains 0.2% of the quantity of Zinc-65 



124 PROC. FOURTH EUROP. MALAC. CONGR. 

introduced, the anodontae 6.2% and the sediment 93.6%. 

Although the specific activities of the soft tissues and the shell vary from one 
specimen to another throughout the whole experiment they remain within particular 
limits. The activity of the internal liquids decreases as the activity of the water 
decreases. The haemolymph always has a distinctly greater specific activity than 
the palleal and extrapalleal liquid. The classification of the internal organs, in terms 
of their decreasing specific activities, is as follows: 

1) Gills 4) Mantle edge 

2) Palps 5) Visceral mass 

3) Siphons 6) Muscular mass 

The average concentration factors representing the proportion between the activity 
of the organ and the activity of the water, in a state of balance, are as follows: 

Entire shellfish - 955 
Shell - 230 

Soft parts = 3220 

Internal liquids - 30 
Blood = 50 Visceral mass = 2620 

Muscular mass - 2470 

The radio-zinc's distribution in the organism is as follows: 

With respect to the activity of With respect to the activity of 

the entire shellfish the soft tissues 

Shell = 10 % Visceral mass = 40% 

Soft tissues = 88.5% Gills and palps - 35% 

Internal liquids = 1.5% Mantle -15% 

Muscular mass - 10% 

Anodontae fix Zinc-65 very strongly and can be used, if necessary, as indicators of 
environmental contamination. The shell keeps the Zinc-65 mainly through adsorption 
mechanisms. On the other hand, the gills and the outer part of the mantle are the 
organs preferred for fixation and storage; the haemolymph seems to play an essential 
part in transporting the zinc. 



Gills 


- 7240 


Palps 


= 2530 


Siphons 


= 3140 


Mantle edge 


- 2880 



MALACOLOGIA, 1973, 14: 125-127 

PROC. FOURTH EUROP. MA LAC. CONGR. 

THE ROLE OF THE RELATIVE SUSCEPTIBILITY OF SNAILS TO INFECTION 

WITH HELMINTHS AND OF THE ADAPTATION OF THE PARASITES IN THE 

EPIDEMIOLOGY OF SOME HELMINTHIC DISEASES 

J. C. Boray 

1 p 

Department of Parasitology, University of Zürich > 

The presence of specific intermediate hosts is essential for the development of 
some helminths which may cause serious diseases in man and animals. The occur- 
rence, distribution and epidemiology of these diseases depend greatly on the geo- 
graphical distribution of the intermediate hosts and on their relative susceptibility 
to the parasites. All digenetic trematodes have 1 or more intermediate hosts, the 
first of which is always a snail, and they also have single or multiple definitive host- 
species. During the evolutionary process and speciation of various trematodes a 
distinct biological balance has developed between the hosts and parasites. The free- 
living stages exposed to adverse effects of the environment are usually produced in 
enormous numbers (up to 50,000 eggs per day by a single Fasciola hepática). However 
the 1st larval stages often have to find highly specific intermediate snail hosts. During 
the 1st parasitic stages a parthenogenetic multiplication occurs resulting in the re- 
lease of large numbers of the 2nd free-living stage. A single Lymnaea truncatula 
may produce a total of 300-4000 metacercariae of F. hepática which are relatively 
resistant to adverse environmental conditions. The output of the relatively short 
lived Schistosoma mansoni cercariae in Biomphalaria glabrata is 1000-3000 daily. 
Dicrocoelium dendriticum produces fewer but more resistant eggs but a large number 
of 1st intermediate snail hosts are available for their larval development and asexual 
multiplication. 

The relative susceptibility or resistance of the intermediate and/or definitive hosts 
to the various parasites is another factor, which plays a most important role in main- 
taining the biological balance ensuring the survival of both the host and the parasites. 
Members of the family Dicrocoeliidae show little specificity in their 1st intermediate 
hosts. Many species belonging to several families of Stylommatophora have been 
found to be good hosts for the larval development of Dicrocoelium dendriticum. There 
is also little host specificity in the definitive hosts and the epidemiology of dicrocoe- 
liosis is more dependent on the highly specific 2nd intermediate ant-hosts or on other 
ecological factors. Little host specificity has been found in the relationships of some 
nematodes (Metastrongylidae, Angiostrongylus cantonensis and A. vasorum) and ces- 
todes (Davaineidae) to their intermediate snail-host (Stylommatophora), but those 
parasites are more specific in their definitive hosts. The medically important groups, 
such as Schistosomatidae and Fasciolidae, are more host specific in the snails 
(Planorbidae and Lymnaeidae, Basommatophora) than they are in their definitive hosts. 
In most parts of the world Fasciola hepática is transmitted by Lymnaea truncatula and 
F. gigantica by L. auricularia s.l. or by varieties of these insufficiently distinctive to 
be regarded as separate species. A certain species of planorbid or Oncomelania snail 
host is essential for the larval development of various Schistosoma spp., and the 
availability of a suitable intermediate host is further complicated by the different 



1 Winterthurerstrasse 260, CH 8057 Zürich, Switzerland 



2 Present address: Research Centre, Ciba-Geigy Ltd., Western Rd. , Kemps Creek, N. S. W. , 
Australia 

(125) 



126 PROC. FOURTH EUROP. MALAC. CONGR. 

TABLE 1. Host-parasite relationship between Lymnaea and Fasciola spp. 

Absolute resistance: No larval development 

Age resistance: Development only in Termination of infection full 

young snails development of few larvae 

Relative disparity: Full development in Low infection rate - Slow development of few larvae 
adult snails Low infection rate - High mortality of snails 

High infection rate - High mortality of snails 

Normal relationship: Full development in High infection rate - Low mortality of snails 
adult snails 

susceptibility of infra -specific variations of species-complexes of snails to different 
races of the parasites. 

It has been shown that some geographical or microgeographical races of planorbid 
or lymnaeid snails, although susceptible, are not equally competent intermediate hosts 
for different species or strains of Schistosomatidae or Fasciolidae. This relative 
disparity is an important limiting factor in the distribution of a disease (réf.: Jordan 
& Webbe, 1969; Boray, 1969). A considerable effort has been devoted to experimental 
work showing host parasite disparity between infra-specific variations of schistosomes 
and snails (Files & Cram, 1949; Hunter et al., 1952; De Witt, 1954; Hsü & Hsü, 1960, 
1967; Wright, 1962; Paperna, 1968 and most recently Webbe & James, 1971). However, 
it has been shown in laboratory experiments by Boray (1967, 1969) that in newly formed 
relationships between trematodes and an unusual snail host, the adaptation of the 
trematode can occur rapidly as a result of passage, such as the European Fasciola 
hepática in the Australian Lymnaea tomentosa and the Australian F. hepática in L. 
tomentosa from New Guinea, or rather slowly, such as F. hepática in L. peregra, the 
latter showing a strong age resistance. Boray (1969) concluded that in newly formed 
relationships between trematodes and an unusual snail host, the adaptation of the 
trematode might occur very rapidly as a result of passage if the snails have a degree 
of susceptibility in their adult stage. 

Various manifestations of a relationship between lymnaeid snails and Fasciola 
spp. (Table 1) may be similar in other snail-trematode relationships. It would be 
most important that similar studies should be carried out with the medically impor- 
tant schistosome-snail combinations showing relatively low susceptibility. In some 
of the less competent race combinations within established specific relationships the 
disparity may be only temporary. Most trematodes have a long life span in their 
definitive hosts, and if some fasciolids were introduced by domestic animals or some 
schistosome strains were introduced by movements of human populations into new 
areas, they may adapt readily to a relatively less susceptible snail through passages, 
thus creating new problems in disease control. 

REFERENCES 

BORAY, J. C, 1967, Proc. 3rd int. Conf . Wld. Assoc. Advmt. vet. Parasitol., Lyon, 1967 

(Vet. med. Rev.) p 132-140. 
BORAY, J. C, 1969, Adv. Parasitol, 7: 95-210. 
DE WITT, W. В., 1954, J. Parasitol., 40: 453-456. 
FILES, V. S. & CRAM, E. В., 1949, J. Parasitol., 35: 555-560. 
HSU, S. Y. Li & HSU, H. F., 1960, J. Parasitol., 46: 793. 
HSU, H. F. & HSU, S. Y. Li, 1967, Z. Tropenmed. Parasitol., 18: 417-432. 



BORAY 12 7 

HUNTER, G. W. Ill, RITCHIE, L. S. & OTONI, Y., 1952, J. ParasitoL, 38: 492. 
JORDAN, P. & WEBBE, G., 1969, Human Schistosomiasis. Heinemann, London, 1969 
PAPERNA, I., 1968, Ann. trop. Med. ParasitoL, 62: 13-26. 
WEBBE, G. & JAMES, C., 1971, C.r. 1er Multicolloque de parasitol. Rennes, 1971 (In 

print). 
WRIGHT, C. A., 1962, In: "Bilharziasis: Ciba Foundation Symposium", p 103-120, 

Churchill, London. 



MALACOLOGIA, 1973, 14: 129-133 

PROC. FOURTH EUROP. MALAC. CONGR. 

EFFETS DE LA CASTRATION CHIRUGICALE SUR LE TRACTUS GENITAL 

ET LA PONTE CHEZ LES AEOLIDIIDAE: APPLICATION A LA COMPREHENSION 

DES MECANISMES DU CONTROLE ENDOCRINE DE LA SEXUALITE 

J. Tardy 

Laboratoire de Biologie et Biochimie Marines 
Université de Poitiers, France 

A la suite des interventions que j'ai pratiquées chez les Aeolidiidae , j'ai pu noter 
quelques faits qui méritent d'être signalés et discutés à la lumière des observations 
faites dans d'autres groupes, en particulier récemment, chez les Prosobranches par 
Streiff (1967), Streiff et Le Breton (1970 a et b) et chez les Basommatophores, par 
Harry (1965) et par Brisson (1970 et 1971). Sans faire l'exégèse des nombreux travaux 
effectués chez les Pulmones et les Prosobranches, résumons les résultats auxquels 
ont abouti les recherches: pour les uns, le tractus est indépendant de la gonade, pour 
les autres, au contraire, la dépendance serait étroite. En fait, comme l'exprime 
Streiff (1970 c), la contradiction ne pourrait être qu'apparente, car les travaux sur les 
Prosobranches portent sur la différenciation, les autres sur le fonctionnement du 
tractus glandulaire. 

Mes observations permettent d'affirmer cette opinion. Auparavant, il convient de 
remarquer qu'aucun Aeolidiidae castré ne dépose la moindre ponte et qu'il faut 
attendre, chez ceux qui régénèrent, l'émission des ovocytes pour que se restaure le 
processus. Pourtant, dans les conditions d'élevage, des pontes sans germe ou parti- 
ellement pourvues de germes sont parfois déposées par des Aeolidiella alderi indemnes. 
Quelquefois les oeufs sont éclatés: la ponte renferme alors un véritable cordon de 
vitellus qui n'évolue pas et devient vite la proie de bactéries. 

Selon les espèces, chez les Basommatophores castrés, des pontes sans germes 
sont déposées assez souvent ou rarement (Brisson, 1970-1971). 

Cependant, comme l'a observé cet auteur chez les Basommatophores, et moi-même 
chez les Aeolidiidae, l'instinct d'accouplement subsiste (au moins chez certains indi- 
vidus). 

Que révèlent la dissection et Г étude histologique du tractus génital chez les Aeoli- 
diens castrés définitivement? 

1) Tractus mâle: Le pénis semble peu affecté par la castration; par contre le 
spermiducte montre des variations importantes du développement des epitheliums 
glandulaires, surtout dans sa partie proximale (prostatique). 

2) Tractus femelle: Les glandes responsables de la formation de la ponte demeurent 
parfois à l'état d'ébauches (Fig. 1) et n'acquièrent pas de différenciation cytologique; 
plus généralement elles ont un volume normal ou sont hypertrophiées. Dans ces deux 
cas elles présentent un aspect cytologique pathologique. 

Les cellules prennent une forme sphérique, se détachent et tombent dans la lumière 
où elles forment un coagulum nécrotique qui remonte pari ois vers la glande gamétoly- 
tique où il est phagocyté par l'épithélium qui augmente considérablement d'épaisseur. 

Cet aspect des glandes nidamentaires se retrouve chez tout sujet ne produisant 



1 Sept types principaux d'intervention représentant plus de 150 observations individuelles, portant 
sur Aeolidia papulosa, Aeolidiella glauca, Ae. sanguínea et surtout sur Ae. alderi. 



(129) 



130 



PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 1. Tractus génital d'Aeolidiella glauca récoltée et opérée alors qu'elle était en phase 
juvénile et sacrifiée 66 jours plus tard: Le tractus mâle, la vésicule séminale et la spermathèque 
sont normalement développés. Par contre, les glandes annexes femelles sont totalement indif- 
férenciées et n'ont pas évolué. ° 

c. çf : Canal hermaphrodite, gl. a. : glandes annexes; n. c. : nodule cicatriciel au niveau de la 
section du canal hermaphrodite; o.g.: orifice génital; pé: pénis; spd: spermiducte; spth: glande 
gamétolytique; vs: vésicule séminale. 

plus de gamètes à la suite de diverses interventions, en particulier chez les individus 
en régénération, dont les glandes étaient déjà fonctionnelles lors de l'opération. Dans 
ce cas, une partie de Г epithelium semble alors proliférer et remplacera probable- 
ment la portion en voie de nécrose. 

Lorsque ces glandes étaient encore juvéniles à la castration, elles subissent un 
retard considérable dans leur développement si la gonade régénère. A la suite de 
ces observations nous pouvons supposer que l'absence totale du dépôt de la ponte 
pourrait s'expliquer par une double action de la castration: blocage de la différen- 
ciation glandulaire lorsque l'opération a lieu assez tôt, ou bien si celle-ci survient 
après la différenciation glandulaire, perturbation du fonctionnement entraînant une 
dégénérescence plus ou moins marquée des glandes nidamentaires. 

Dans ce cas, comme l'a exprimé Brisson (1970 et 1971) à propos des Basommato- 
phores, il semble bien que le fonctionnement normal de ces glandes ne soit pas sous 
le contrôle hormonal de la gonade, mais dépende plutôt de son bon fonctionnement 
exocrine: en effet si l'on implante une gonade à un individu préalablement castré, ou 
bien si l'on sectionne le canal hermaphrodite à un individu indemne, la glande nida- 
mentaire s' hypertrophie et dégénère. 

Le blocage de la différenciation glandulaire du tractus par la castration montre 
bien qu'il y a, chez les Gastéropodes, une action hormonale de la gonade qui agit 
directement ou indirectement sur la cytodifférenciation du tractus femelle et peut- 
être également sur celle du tractus mâle. 

Un autre point est particulièrement frappant et suggestif: il apparaît nettement que 
les tractus mâle et femelle évoluent indépendamment (Fig. 1 et 2). Ces dernières 
observations sont, elles aussi, en accord avec les remarquables travaux de Streiff 
(1967), qui a montré in vitro chez les Prosobranches que le développement du tractus 
mâle et du tractus femelle est régi par des substances hormonales différentes, émises, 
pour le premier, par le tentacule, pour le second, par le système nerveux. 

Chez Calyptraea, sinensis, Prosobranche à hermaphrodisme successif, Streiff 
(1967) a montré par des associations en cultures d'organes que l'évolution du tractus 
femelle est déclenchée par une substance hormonale émise par les ganglions céré- 



TARDY 



131 




FIG. 2. Tractus génital d'Aeolidiella alderi opérée alors qu'elle était en fin de phase juvénile et 
fixée 115 jours plus tard. La partie mâle est cytologiquement différenciée mais faiblement dé- 
veloppée; le pénis est sub-normal, les glandes annexes sont différenciées, gl. m: glande mu- 
queuse: gl. a. : glande de l'albumine (pour les autres abréviations, se reporter à la Fig. 1). 



broides pendant un temps très court, lorsque se produit le changement de sexe. A la 
suite de cette impulsion la cytodifférenciation se poursuit d'elle-même. 

Ce résultat explique parfaitement, à mon sens, les observations faites chez les 
Pulmones et les Nudibranches où les individus castrés présentent un tractus cytolo- 
giquement différencié ou non, si l'on admet l'hypothèse suivante: c'est la gonade qui 
provoque par l'intermédiaire du cerveau l'émission d'une ou de plusieurs substances 
inductrices du développement du tractus femelle. 

Si la castration survient avant que la gonade ait déclenché cette émission, le tractus 
reste juvénile; dans le cas contraire, le tractus acquiert une cytodifférenciation fonc- 
tionnelle, mais son fonctionnement est plus ou moins fortement perturbé par l'absence 
de production de gamètes. 

L'impulsion hormonale doit survenir très tôt, car la majorité des individus que 
j'ai castrés ont un tractus développé. D'autre part, bien que Brisson ait opéré des 
individus aussi jeunes que possible, il n'a jamais observé d'inhibition du développe- 
ment du tractus chez les Basommatophores. Seul Harry (1965) semble y être parvenu. 

D'autre part, il est possible que lors de l'organogénèse naturelle le massif méso- 
dermique soit l'inducteur morphogénétique direct ou indirect du tractus femelle. 
Par contre, il ne semble pas être le déterminant morphogênétique du tractus mâle 
ainsi que le montrent les expériences in vitro pour les Prosobranches (du moins 
directement) et les cas d'aphallie, (règle courante chez certaines races de Bulinus 
par exemple) de biphallie symétrique ou autres anomalies constatées de temps en 
temps chez divers Pulmones. 

En résumé, il semble hors de doute que la gonade soit à l'origine des mécanismes 



132 PROC. FOURTH EUROP. MALAC. CONGR. 

de fonctionnement du tractus. Son rôle serait indirect; il déterminerait l'élaboration 
d'une ou de plusieurs hormones par le système nerveux. Celle(s)-ci provoquerai! en)t: 
(1) la cytodifférenciation du tractus femelle, (2) très probablement celle du tractus 
glandulaire mâle. 

Enfin pour prouver la réelle indépendance de la morphogenèse du tractus chez les 
formes hermaphrodites, (où le déterminant génétique est probablement éliminé) il 
serait intéressant de supprimer l'ébauche gonadique de larves avant que ne se forme 
le bourgeon ectodermique. Une telle opération est très difficile à réaliser, mais elle 
est susceptible d'apporter des résultats déterminants. 

SUMMARY 

SURGICAL CASTRATION OF THE GENITAL TRACT AND THE SPAWN OF THE 

AEOLIDHDAE: AN ATTEMPT TO UNDERSTAND THE MECHANISMS 

OF SEXUAL ENDOCRINE CONTROL 

Surgical castration in the Aeolidiidae has given the following results: 1) No spawn 
is ever laid by these castrated sea-slugs; 2) From the cytological point of view, after 
a certain amount of time, the female tract can have one of two opposite appearances: 
a) glandular differentiation does not appear, or, b) most of the time, differentiation 
does appear. 

In the case of differentiation there is a hypertrophic female tract, the elements of 
which are usually and in greater part degenerated, and fall into the lumen. They then 
seem to go to the "gametolytic gland" where they are probably digested. 

3) Observation also shows that male and female tracts of the same animal can 
have an opposite cytological aspect, either differentiated or not. This fact confirms 
that each one depends on a different endocrine control for cytological differentiation 
as Streiff (1967) has shown in the prosobranchs. 

All of these observations are discussed and compared with the results obtained with 
other gastropods. They suggest some modifications of the diagram proposed to ex- 
plain the mechanisms which control differentiation, maturation, and interactions of 
the different parts of the tract. 

BIBLIOGRAPHIE 

BRISSON, P., 1967, La castration chirurgicale chez Bulinus (contortus Michaud) 
truncatus (Audouin) Mollusque Gastéropode Pulmoné. Cr. hebd. Séanc. Acad. 
Sei. Paris, 264: 131-133. 

BRISSON, P., 1970, Contribution à l'étude des corrélations entre les différentes 
régions de l'appareil génital, par castration, ablation, implantation, chez quel- 
ques Mollusques Gastéropodes Pulmones Basommatophores et principalement 
chez Bulinus truncatus (Audouin). Thèse Doct. Sei. Nat. Poitiers. Arch. orig. 
centre documentation CNRS No 4320, juin 1970, 154 p, 14 pi. h. t. 

BRISSON, P., 1971, Castration chirurgicale et régénération gonadique chez quelques 
Planorbidês (Gastéropodes Pulmones). Ann. Embryol. morphogen. 4, 2: 189-210. 

HARRY, H. W., 1965, Evidence of a gonadal hormone controlling the development of 
the accessory reproductive organs in Taphius glabratus (Say). (Gastropoda, 
Basommatophora). Trans. Amer, microsc. Soc. 84, 1: 157. 

LA VIOLETTE, P., 1954, Rôle de la gonade dans le déterminisme humoral de la 
maturité glandulaire du tractus génital chez quelques Gastéropodes Arionidae 
et Limacidae. Bull. biol. Fr. Belg., 88: 310-332. 

LE BRETON, J., 1971, Nature endocrine des substances responsables de l'organo- 



TARDY 133 

genèse et du cycle des tractus génitaux chez les gonochoriques et les herma- 
phrodites (colloque sur la sexualité des Mollusques). Haliotis 1, 2: 215-228. 

LUBET, P. & STREIFF, W., 1969, Etude expérimentale de l'action des ganglions 
nerveux sur la morphogénèse du pénis et l'activité génitale de Crepidula forni- 
cata Phil. (Mollusque Gastéropode). In: Cours et documents de Biologie, Gordon 
& Breach. 

STREIFF, W., 1967, Recherches cytologiques et endocrinologiques sur le cycle sexuel 
de Calyptraea sinensis L. (Mollusque Prosobranche hermaphrodite protandre). 
Thèse (261 p, 29 pi.) 

STREIFF, W., 1970, Analyse expérimentale de la différenciation sexuelle chez les 
Mollusques Gastéropodes. Conférence au Collège de France, 43 p. 

STREIFF, W. & LE BRETON, J., 1970a, Etude endocrinologique des facteurs régissant 
la morphogénèse et la régression du pénis chez un Mollusque Prosobranche 
gonochorique, Littorina littorea L. C.r. hebd. Séanc. Acad. Sei. Paris, 270: 547- 
549. 

STREIFF, W. & LE BRETON, J., 1970b, Etude comparée en culture in vitro des fac- 
teurs responsables de la morphogénèse et de la régression du tractus génital 
mâle externe chez deux Mollusques Prosobranches: Crepidula fornicata (Phil) 
(espèce protandre) et Littorina littorea L (espèce gonochorique). C.r. hebd. 
Séanc. Acad. Sei. Paris, 270: 632-634. 

TARDY, J., 1965, Spermatophores chez quelques espèces d'Aeolidiidae (Mollusques 
Nudibranches). C.r. Séanc. Soc. Biol., 160: 369-371. 

TARDY, J., 1967, Organogenese de l'appareil génital duMollusque Nudibranche Aeoli- 
diella alderi (Cocks). C.r. hebd. Séanc. Acad. Sei. Paris, 265: 2013-2014. 

TARDY, J., 1967, Régénération de la gonade après castration chirurgicale chez 
quelques Aeolidiidae (Mollusques Nudibranches). C.r. Séanc. Soc. Biol., 161: 
2013-2016. 

TARDY, J., 1969a, Etude systématique et biologique sur trois espèces d'Aeolidielles 
des côtes européennes (Gastéropodes Nudibranches). Bull. Inst. ocêanogr. 
Monaco, 68: 1389, 40 p, 15 pi. 

TARDY, J., 1969b, Contribution à l'étude des Nudibranches. Thèse de Doct. d'Etat, 
Sei. Nat. Arch. orig. centre document. Poitiers 4 juillet 1969, CNRS No3287, 
196 p, 9 pi. h.t. 

TARDY, J., 1970a, Organogenese de l'appareil génital chez les Mollusques. Bull. 
Soc. zool. Fr., 95, 3: 407-428. 

TARDY, J., 1970b, Contribution à l'étude des métamorphoses chez les Nudibranches. 
Ann. Sei. natur. (Zool.) B.A. 12ème série, 12: 299-371. 

TARDY, J., 1971a, Embryologie et Organogenese sexuelle. (Colloque sur la sexualité 
des Mollusques) Haliotis 1, 2: 151-156. 

TARDY, J., 1971b, Etude expérimentale de la régénération germinale après castration 
chez les Aeolidiidae. Ann. Sei. natur. (Zool.) B.A. 12 série, 13, 1: 91-147. 



MALACOLOGIA, 1973, 14: 135-142 

PROC. FOURTH EUROP. MA LAC. CONGR. 

STUDIES OF THE ENDOCRINE CONTROL OF THE REPRODUCTIVE TRACT 
OF THE GREY FIELD SLUG AGRIOLIMAX RETICULATUS 

N. W. Runham, T. G. Bailey and A. A. Laryea 

Department of Zoology, University College of North Wales 
Bangor, Caernarvonshire, U.K. 

INTRODUCTION 

Pulmonate slugs are protandric hermaphrodites. Many species complete 1 breeding 
cycle, then die, but some may complete 2 such cycles, e.g., Milax gagates (Galangau, 
1964). In very young animals the simple sac -like gonad is full of apparently undif- 
ferentiated cells. As the animals get older the gonad becomes increasingly lobed, 
then first oocytes become visible followed by differentiating sperm and nutritive cells. 
At first the oocytes enlarge slowly while there is very rapid production of large num- 
bers of sperm. When most of the sperm have been shed the ova mature. Reproductive 
tract maturation is very closely related to this sequence in the gonad. The prostate 
gland matures preparatory to the male phase of the gonad and functions at copulation. 
Egg laying is preceded by the maturation of the albumen and oviducal glands. In most 
species, e.g., Arion ater (Lusis, 1961; Smith, 1966), there is a very clear separation 
of the male and female phases of the cycle, but in Agriolimax reticulatus there is often 
some overlap (Runham & Laryea, 1968). 

The relation between the gonad and reproductive tract has been extensively studied 
by Laviolette (1954). Using various arionid and limacid species with well defined 
seasonal breeding periods he carried out an extensive series of organ transplants. 
The gonad or the reproductive tract from a species at one stage of development was 
transplanted into the body cavity of another species which at that time of year was at 
a different stage of its reproductive cycle. Laviolette observed that an immature tract 
transplanted into a 'mature' animal showed a marked enlargement. He deduced, 
therefore, that there was a hormone in the blood which controlled the maturation of 
the reproductive tract. 

In this study Agriolimax reticulatus was used as it will breed all the year round, so 
all stages of reproductive maturation are available in the one species. It is also usu- 
ally available in large numbers and can be maintained in the laboratory fairly readily. 

MATERIALS AND METHODS 

Agriolimax reticulatus were collected from various localities within a 3-mile 
radius of the Department. Most of the larger animals used for operations were col- 
lected from the wild, but as small animals are very difficult to collect laboratory 
cultures were set up for these. The cultures were maintained in either polystyrene 
sandwich boxes or polythene washing-up bowls, in both cases filled to a depth of 3-5 
cm with sterile soil and having a small aperture covered with gauze in the cover. 
Animals were usually fed on carrot but also occasionally on lettuce, and cleaned at 
least twice a week. The only difficulty encountered with the cultures was at the start 
of the experiments when there was a very high incidence (about 90%) of infection with 
Tetrahymena in locally collected animals. It was found to be impossible to control 
this parasite, which can be transmitted in the egg, but luckily, for no apparent reason, 
the incidence of infection in the local population later fell to a very low level. 

(135) 



136 



PROC. FOURTH EUROP. MALAC. CONGR. 



For all operations the slugs were anaesthetised with carbon dioxide (Bailey, 1969). 
They were then placed on moist filter paper on the stage of a Zeiss Stereomicroscope 
HI with foot-operated focussing control. Fine forceps, needles and de Wecker iridec- 
tomy scissors were the only instruments required for the operations. 

a) Sampling the gonad. A small cut was made in the body wall at the point A (Fig. 1); 
the very deeply pigmented gonad was located and a small piece removed. 

b) Castration. The gonad was located as in a); then it was carefully separated from 
the digestive gland by tearing the connective tissue sheaths and membranes. The main 
difficulty with this operation is avoiding damage to the overlying rectum particularly 
when the gonad is pulled out from beneath it. Once the gonad has been separated from 
the surrounding tissues it is pulled, if possible forwards, then the hermaphrodite duct 
is cut and the gonad removed. In some cases the gonad had to be removed in 2 pieces 
because of its size, the region posterior to the rectum and the region anterior to it. 
Occasionally there are rather small and isolated groups of acini at the anterior edge 
of the gonad and these were easily left behind. This was always checked at the con- 
clusion of the experiment. Regeneration of the gonad from the cut end of the herma- 
phrodite duct occurs as in other slugs (Laviolette), but very rarely was there any 
sign of differentiation by the end of the experiment. 

c) Transplants. The transplants (see below) were manipulated under medium and 
taken up into the end of a trochar needle. A small hole was cut in the body wall at 
point В (Fig. 1), the trochar inserted and the transplant injected. The body was held 
against the tip of the trochar when it was removed in case the transplant adhered to 
the needle. 




FIG. 1. Agriolimax reticulatus . A, position of the incision for removal of the gonad; B, posi- 
tion of the incision for the injection of the transplant. 



In none of these operations were any sutures needed in the body wall. After the 
operation the animals were transferred individually or in small groups to disposable 
petri dishes lined with moistened filter paper and containing a piece of carrot. Ani- 
mals were usually wandering around the dish within 30 minutes of operation. 

The transplants were obtained from very small animals that had a reproductive 
tract in the earliest stage of differentiation. After anaesthesia animals were dissected 
under either Hedon-Fleig saline or organ culture medium (Bailey, 1972). The common 
duct, in some cases with the albumen gland attached, was removed and cut into 2-7 
pieces, one of which was immediately fixed, while the others were transplanted. 
Transplanting occurred 10-60 minutes after dissection. 

At the end of the experiment anaesthetised animals were opened along the length of 
the body and the transplant searched for in the haemocoel, particularly in the region 
of the brain and buccal mass. In some cases where the transplant had formed a large 
swollen cyst it was readily found, but in castrates the very small pieces of tract were 
exceedingly difficult to discover. The transplant together with the host gonad and 
sometimes the reproductive tract were fixed. 

Tissues were either fixed in susa, washed and dehydrated in cellusolve and embedded 
in ester wax, or fixed in buffered osmium and embedded in Araldite. Ester wax sec- 
tions (7a¿) were stained with Azan and 1-3 ju Araldite sections were stained with 



RUNHAM, BAILEY and LAR YEA 137 

toluidine blue. The stages in the maturation of the gonad and reproduction tract have 
been described elsewhere (Runham & Laryea, 1968). 

RESULTS 

It was hoped originally to produce quantitative data for the enlargement of the glands 
and for any histological changes resulting from transplanting. For the following rea- 
sons this proved to be impossible. Because of a lack of clear separation of the male 
and female stages in this species the determination of some stages in the development 
of the gonad was less accurate than with others. No problems were encountered with 
the spermatocyte, spermatid, early sperm, late oocyte and post-reproductive stages. 
The separation of late sperm and early oocyte stages however is dependant on the 
relative quantities of sperm and oocytes and the size of the latter. In some late sperm 
stages, with large amounts of sperm present, only a few oocytes were visible - far 
fewer than normal - probably indicating that in these animals some egg laying had 
taken place before the more normal loss of the majority of the sperm. Because of 
variations in the relative proportions of oviducal and prostate gland tissue along the 
length of the common duct (i.e., oviducal gland predominates at the top of the common 
duct and prostate gland at the bottom) it was impossible to quantify the changes in the 
relative proportions of the 2 glands in the small transplants. Frequently the 2 open 
ends of the transplanted common duct became sealed and secretion by the glands led 
to the formation of a considerably swollen cyst with greatly distorted glands, A sub- 
jective qualitative assessment was therefore developed to assess the changes following 
transplanting with the above features taken into account. 

During normal maturation of the reproductive tract the prostate gland develops first. 
Diverticulae are formed which enlarge, and then the cubical epithelium becomes under- 
lain by cells which differentiate into a number of different types of secretory cell. 
Only when secretion has appeared in the prostate does differentiation of the oviducal 
gland begin. Cells appear beneath the cubical epithelium lining of the oviducal gland 
which differentiate to become grossly distended with secretion. 

Castrated animals were left for a week to recover from the operation and then a 
piece of common duct from a very young animal was transplanted into the haemocoel. 
Due to the very small size of these transplants they were only recovered from 6 
animals, but in no case was there any increase in size of the common duct after 10 
days compared to the controls. The results from 3 series of experiments on normal 
hosts are given in Tables 1, 2 and 3. When a tract from a very young animal, showing 
only the earliest stages in the differentiation of the prostate gland, was transplanted 
into the haemocoel of an animal at a later stage of development and left there for 10 
days, rapid transformation of the transplant occurred. In the spermatid stages there 
was a slight enlargement, while in early sperm and the earliest of the late sperm 
stages development of the prostate was pronounced (Fig. 2). During the very late 
sperm stage both the oviducal and prostate glands matured. In the oocyte stages the 
oviducal gland shows maximum enlargement and secretion while the prostate gland 
enlarges slightly (Fig. 3). In the post-reproductive stages the oviducal gland alone 
matured. In normally developing common ducts the oviducal gland matures only 
after the prostate gland has completed its maturation. 

DISCUSSION 

As the transplants were left free in the haemocoel, the factors causing the observed 
changes must be blood-borne, i.e., they are hormones. The results obtained indicate 
the existance of 2 hormones, one responsible for the maturation of the prostate gland 



138 



PROC. FOURTH EUROP. MALAC. CONGR. 



- - 



4 






*\ 



%^ 




■ «ик;^. <.-'■ jL* 







•• 



1*C 









%> 




> 






* 



FIG. 2. Agriolimax reticulatus . Common duct transplant 10 days after placing in the haemo- 
coel of an early male stage host. Inset, control piece of common duct fixed at the time of 
transplanting. P, prostate gland; O, oviducal gland. 

FIG. 3. Agriolimax reticulatus . Common duct transplant 10 days after placing in the haemo- 
coel of an early female stage host. Inset, control piece of common duct fixed at the time of 
transplanting. P, prostate gland; O, oviducal gland. 



RUNHAM, BAILEY and LARYEA 



139 



TABLE 1. Agriolimax reticulatus . Fate of pieces of immature common duct transplanted into 
the haemocoel of older animals. 



Series 1 





Prostate Gland 


Oviducal Gland 


Common Duct 


Host 
Stage 


% Expansion 


Secretion 


% Expansion 


Secretion 


Male 
Characteristics 


Female 
Characteristics 



D 


150 


D 


300 


D 


300 


D 


500 


E 


600 


E 


1,650 


E 


1,500 


E 


700 


E 


4,000 


E 


200 


F 


400 


G 


4,000 


G 


1,000 


G 


300 


G 


200 


H 


350 


H 


150 


H 





H 






500 
500 



- 


- 


++++ 


- 


- 


++++ 


700 


+ 


+++ 


4,000 


++ 


++++ 


2,000 


+++ 


+ 


1 


+++ 


+ 


4,000 


+++ 


++++ 


1,000 


++ 


++ 


1,500 


++++ 


++ 


400 


+++ 


+ 


1,000 


++++ 


++ 


2,500 


++++ 


+ 



++ 

+++ 

+++ 

++++ 

+++ 

++++ 

+++ 

++ + + 

+++ + 

+ + 4 + 



1,000 



Stages of maturation of the host gonad are:- D early spermatozoon, 
E late spermatozoon, F early oocyte, G late oocyte, H post-reproductive. 
The amount of secretion is indicated by the number of + symbols and 
the absence of secretion by -. The male characteristics of the common 
duct is a subjective assessment based on the percentage expansion, 
amount of secretion and the histology of the prostate gland; while 
the female characteristics is similarly based on the oviducal gland. 



700- 



— prostatic hormone 
■-- oviducal hormone 




В С D E F 

Hermaphrodite gland stage 



FIG. 4. Agriolimax reticulatus . Suggested timing for the secretion of prostatic and oviducal 
hormones in relation to the stage of development of the hermaphrodite gland. A , undifferen- 
tiated; B, spermatocyte; C, spermatid; D, early spermatozoon; E, late spermatozoon; F, early 
oocyte; G, late oocyte; H, post-reproductive. 



140 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLE 2. Agriolimax reticulatus . Fate of pieces of immature common duct transplanted into 
the haemocoel of older animals. 



Series 2 





Prostate Gland 


Oviducal Gland 


Common Duct 


Host 
Stage 


% Expansion 


Secretion 


% Expansion 


Secretion 


Male 
Characteristics 


Female 
Characteristics 



D 


400 


E 





E 


500 


E 


200 


E 


800 


E 


150 


E 





E 


400 


E 


250 


F 


400 


F 


300 


G 


500 


G 


150 


G 


500 


G 


400 


H 


1,000 


H 


700 


H 





H 






500 


- 


+ 








- 


400 


- 


++ 





- 


+ + 





- 


+ + 


1,000 


4— 


+ 


500 


+ - 


+ + 


200 


- 


++ 


? 


- 


+ 


200 


- 


+ 


700 


+ 


+ 


600 


++ 


+ + 


300 


? 


+ 


500 


? 


+ 


1,000 


+ + + + 


+ 


1,000 


+ + + 


++ 


3,000 


+ + + + 


++ 


1,000 


++++ 


- 


1,600 


+ + + + 


- 



++++ 
+ + + 
+ + + + 
+ + + + 
+ ++ + 



Stages of maturation of the host gonad are:- D early spermatozoon, 
E late spermatozoon, F early oocyte, G late oocyte, H post-reproductive. 
The amount of secretion is indicated by the number of + symbols and the 
absence of secretion by -. The male characteristics of the common duct 
is a subjective assessment based on the percentage expansion, amount of 
secretion and the histology of the prostate gland; while the female 
characteristics is similarly based on the oviducal gland. 



and the other for the oviducal gland (Fig. 4). The prostate hormone appears during the 
late spermatocyte or at the beginning of the spermatid stage and reaches a maximum 
during the spermatozoan stages. During the late sperm stage, at about the time the 
amount of prostatic secretion begins to decrease, the oviducal hormone appears and 
rapidly reaches its maximum. Prostatic hormone appears to be present only in small 
amounts during the oocyte stages and may be absent from post-reproductive animals. 
The processes leading to the maturation of the glands are complex and involve at 
least the following processes: cell proliferation, with cell migration leading to tissue 



RUNHAM, BAILEY and LARYEA 



141 



TABLE 3. Agriolimax reticulatus. Fate of pieces of immature common duct transplanted into 
the haemocoel of older animals. 









Series 3 








Prostate Gland 


Oviducal Gland 


Common Duct 


Host 
Stage 


% Expansion 


Secretion 


% Expansion 


Secretion 


Male 
Characteristics 


Female 
Characteristics 



D 


200 


- 




200 


- 


+ 


E 


300 


- 







- 


++ 


E 


250 


++ 




250 


- 


++ 


E 


300 


++ 







- 


++ 


E 


400 


++ 




300 


+ 


++ 


E 


300 


+ - 


1 


,000 


+ 


++ 


E 


300 


+ 




500 


- 


++ 


E 


300 


++ 




200 


+ + 


++ 


E 


600 


++++ 




200 


- 


+++ + 


E 


300 


+++ + 




400 


+ 


++++ 


E 


? 


1 




500 


++++ 


- 


E 


300 


++ 




400 


++++ 


++ 


E 


400 


+ + 




600 


++++ 


++ 


E 


300 


+ 




400 


++++ 


++ 


E 


500 


++ 




500 


++++ 


++ 


E 


300 


++ 


10 


,000 


++++ 


++ 


F 


150 


- 




400 


- 


- 


F 


300 


- 




600 


++++ 


+ 


H 





+ 


10 


,000 


++++ 


+ 


F 


150 


+ 




400 


++++ 


++ 


H 


500 


+ - 


1 


,000 


++++ 


+ 



++ 

++++ 

++++ 

++++ 

++++ 

++++ 

++++ 

+ 

++++ 

++++ 

++++ 

++++ 



Stages of maturation of the host gonad are:- D early spermatozoon, 
E late spermatozoon, F early oocyte, G late oocyte, H post-reproductive. 
The amount of secretion is indicated by the number of + symbols and the 
absence of secretion by -. The male characteristics of the common duct 
is a subjective assessment based on the percentage expansion, amount of 
secretion and the histology of the prostate gland; while the female 
characteristics is similarly based on the oviducal gland. 



and organ differentiation, and cell differentiation leading to the formation of secretion 
by the cells. In the transplants, even in the short period of 10 days, massive enlarge- 
ment and differentiation both of tissues and cells took place. In some cases it was 
obvious that differentiation of the cells could occur apparently independently of the 
other processes. Thus several examples were noted of cell differentiation in the pro- 
state without any apparent increase in the size of the gland compared to the controls; 
and in addition other examples were found where enormous enlargement of the gland 
occurred with no, or very little, secretion being formed in the cells. There are sev- 
eral possible explanations for this phenomenon. The effect of the hormone may vary 



142 PROC. FOURTH EUROP. MALAC. CONGR. 

with its concentration, or formation of secretion is controlled by a different hormone 
to that controlling organ differentiation. In the case of the prostate gland it is even 
possible that the oviducal hormone may affect formation of prostatic secretions. Not 
enough data was however available for an analysis of this problem. 

Laviolette (1954) clearly demonstrated that the maturation of reproductive tracts 
of a variety of limacid and arionid slugs were under hormonal control. This study 
confirms and extends Laviolette's findings, indicating at least in Agriolimax reticulatus 
that not less than 2 hormones are involved in the maturation of the common duct. The 
albumen gland was also found by Laviolette to be under hormonal control. In our 
experiments information on the albumen gland was obtained only in the first series 
of experiments, and in these enlargement of the gland and the formation of secretion 
occurred in the latest of the spermatozoan stage and in all the oocyte and post- 
reproductive stages. This would perhaps indicate that the albumen gland is also 
influenced by the oviducal hormone. 

The source of these hormones is unknown. Laviolette injected extracts of the gonad 
into various slugs but the reproductive tract did not appear to be affected. Prelimi- 
nary organ culture experiments (Bailey, 1973) indicate that when the gonad and 
reproductive tract are cultured in close proximity no maturation changes can be 
observed in the reproductive tract. However, when the brain, gonad and reproductive 
tract are cultured close together then maturation changes can be observed in the cells 
of the reproductive tract. When Laviolette transplanted gonads from mature slugs into 
castrated immature slugs, maturation of the host reproductive tract resulted. There 
is therefore tentative evidence that factors are produced by the gonad which cause the 
brain to produce the prostatic and oviducal hormones. 

Further experimental studies are clearly needed to clarify the details of hormonal 
control of the reproductive tract of slugs. 

SUMMARY 

An extensive series of organ transplants using the slug Agrioli max re ticulatus indi- 
cate the existence of 2 hormones. When immature common ducts are transplanted 
into the haemocoel of older animals the changes observed in the transplants clearly 
reflect the stage in the reproductive maturation of the host. It is concluded that 1 
hormone controls differentiation and enlargement of the prostate gland, the 2nd hor- 
mone controls the oviducal gland. No changes were observed in common ducts trans- 
planted into the haemocoel of castrated animals. It is suggested that these hormones 
are produced by the brain. 

REFERENCES 

BAILEY, T. G., 1969, A new anaesthetic technique for slugs. Experientia, 25: 1225. 
BAILEY, T. G., 1973, Thez'n m'irocultureof reproductive organs of the slug Agriolimax 

reticulatus (MUH). Neth. J. Zool., 23: 72-85. 
GALANGAU, V., 1964, Le cycle sexuel annual de Milax gagates Drap, (gastéropode 

pulmoné) et ses deux pontes. Bull. Soc. zool. Fr., 89: 510-13. 
LAVIOLETTE, P., 1954, Rôle de la gonade dans le déterminisme glandulaire du 

tractus génital chez quelques gastéropodes arionidae et limacidae. Bull. biol. Fr. 

Belg., 88: 310-32. 
LUSIS, O., 1961, Post embryonic changes in the reproductive system of the slug 

Avion rufus L. Proc. zool. Soc. Lond., 137: 433-68. 
RUNHAM, N. W. & LARYEA, A. A., 1968, Studies on the maturation of the reproductive 

system of Agriolimax reticulatus (Pulmonata: Limacidae). Malacologia, 7: 93-108. 
SMITH, B. J., 1966, Maturation of the reproductive tract of Ar ion ater (Pulmonata: 

Arionidae). Malacologia, 4: 325-49. 



MALACOLOGIA, 1973, 14: 143 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE ANATOMY OF CAVOLINIA INFLEXA (PTEROPODA) 

Joyce E. Rigby 

Queen Elizabeth College, University of London 
Campden Hill, London W. 8, England 

ABSTRACT 

Living and preserved specimens of the thecosomatous pteropod, Cavolinia inflexa have been examined, in 
the young and mature stages. Illustrations of their locomotion and anatomy were presented, and special 
attention has been given to the elaboration of lateral lobes from the mantle margin which probably act as 
balancing structures and accessory surfaces for food collection. A further account of this work will be pub- 
lished elsewhere. 



MALACOLOGIA, 1973. 14: 143 

PROC. FOURTH EUROP. MALAC. CONGR. 

FUNCTIONAL MORPHOLOGY OF THE VERTICORDIIDAE (BIVALVIA) 

J. A. Allen 

Dove Marine Laboratory, Cullercoats, North Shields 
Northumberland, England 

ABSTRACT 

The Verticordiidae are restricted to the deep-sea. They have a characteristic trapezoidal shape and 
usually measure less thanl cm total length. They lie close to the surface of the sediment so that the mantle 
apertures with their arborescent papillate fringing tentacles are level with the sediment surface. The tips 
of the papillae are glandular, the adhesive secretion of which is used in the capture of prey. The latter in- 
cludes copepods and large diatoms. Food is conveyed to the mouth via the gills. The gill filaments are re- 
duced in length and form a pair of vertical ciliated channels leading to the mouth which is surrounded by a 
large, posteriorly directed funnel formed by the greatly modified palps and lips. Oesophagus and stomach 
are highly muscular and forma crushing organ. The stomach is lined with scleroprotein, apart from a nar- 
row ventral ciliated gutter leading to a short style sac. 



(143) 



MALACOLOGIA, 1973, 14: 144-146 

PROC. FOURTH EUROP. MALAC. CONGR. 

CONVERGENT EVOLUTION IN PULMONATE RADULAE 

Alan Solem 

Field Museum of Natural History, Chicago, Illinois, U.S.A. 

ABSTRACT 

Optical examination of radulae is limited by the very shallow depth of field inherent to the light micro- 
scope. This has necessitated mounting the radula in a flattened position between two pieces of glass and 
viewing the squashed specimen from directly above using transmitted light. Where the radula is folded 
under, a glimpse of the side of a tooth may be obtained, but normally it is possible to see only the cusp out- 
lines. Where the cusps are large, they extend backwards over the anterior end of the basal plate in the next 
row, effectively concealing any structures on the basal plate. 

The Scanning Electron Microscope has an effective range of magnification between 14X and 100,000X, its 
depth of field is 300X to 500X that of optical systems, and its resolving power is 12X to 100X greater. When 
coupled with the ability to tilt the specimen from 0°-90° (with the Cambridge Stereoscan but not the Jeolco 
SEM) and rotate it continuously, far more information can be obtained concerning radular structure and 
function. 

To obtain this information requires abandoning previous methods of viewing. The radula should be torn 
and twisted so that lateral views of individual teeth can be seen. It should be folded so that in part the teeth 




FIG. 1. Lateral teeth from the radula of an undescribed West Australian desert camaenid at 1.075X. 



FIG. 2. Upper. Lateral teeth from the posterior end of the radula in Papuina phaeostoma medinensis I. 
Rensch from Lossu Village, Kavieng, New Ireland, Bismarck Archipelago at 1,280X. Lower. Worn lateral 
teeth from the anterior end of the same radula at 1,475X. 

(144) 



SOLEM 



145 




146 PROC. FOURTH EUROP. MALAC. CONGR. 

will be elevated as in a feeding stroke, while elsewhere the teeth lie flat as when they occupy the posterior 
section of the buccal cavity. Since the depth of field obtainable with the Scanning Electron Microscope sub- 
stantially exceeds the field of view dimensions, examination from angles other than the traditional vertical 
study is possible and highly advantageous. 

Preliminary use of the Scanning Electron Microscope in the study of pulmonate radulae has revealed a 
number of significant facts. Most important of these is the existence of a stress support system between the 
rows of teeth. This occurs in a number of families, but varies widely between members of the same family 
and cannot be used to recognize higher taxonomic units. The basic functioning of this support system is as 
follows. When a cusp encounters resistence in cutting or scraping against a food source, the stress is trans- 
mitted to the anterior part of the tooth which is forced down against the basal plate of the tooth in the next 
anterior row. If this tooth is balanced on the odontophoral cartilage tip, then the tip will act as a fulcrum, 
transferring downward pressure on the base to upward pressure on the cusp. Thus resistance encountered 
by one tooth will be applied to the basal plate of the next tooth to come into contact with the food source. 
The process may actually aid the cutting action of this second tooth. Such a mechanism where the action of 
one tooth aids the work of the next is highly efficient. 

When the teeth are viewed from about a 45° angle at a place where the radula has been bent so that the 
sides of some basal plates canbe seen (Fig. 1), the nature of this support system and overlap becomes clear. 
The example used is an undescribed species of camaenid from Western Australia. These are lateral teeth 
shown at a magnification of 1,075X. The tooth at the lower left is resting against the support ridges on the 
next basal plate, as it would under conditions of stress, while the tooth in the center is obviously not under 
stress and is removed from the basal plate contact. 

To date, this phenomenon has been observed in members of the Achatinellidae, Enidae, Pupillidae, Puncti- 
dae, Charopidae, Endodontidae, Partulidae, Cerionidae, Bulimulidae, Achatinidae, Caryodidae, Camaenidae, 
Succineidae, Polygyridae and Helicidae. The details of the support system differ more widely within fami- 
lies than between families in some cases. Thus it cannot be used as a means of determining phyletic rela- 
tionships. The general presence of this mechanism in herbivorous taxa suggests that it may be one of the 
prime reasons for the successful radiation of land snails. 

In carnivorous taxa there is another problem. The long, often sickle-shaped teeth must be folded flat 
when not in use, then elevated to essentially a vertical position in order to slice into the prey. In taxa such 
as Euglandina, the anterior end of the tooth is truncated into a supporting plate that rests against the odon- 
tophore when the tooth is elevated. 

Other problems that are being investigated using the Scanning Electron Microscope include convergent 
evolution in the cusp structure of algal scraping snails, and varying patterns of tooth wear shown by snails 
living under different conditions. In a species of Papuina from the Bismarck Archipelago, for example, the 
newly formed lateral teeth (upper part of Fig. 2) are markedly elevated, with broad, spade-like cusp. At 
the anterior end of the same radula (lower part of Fig. 2) the cusps have been worn down to less than half 
their original height. Scratch lines are clearly visible on the remnant upper edge. The upper figure is at 
1,280X magnification, while the lower figure is slightly larger at 1.475X. 

Use of the Scanning Electron Microscope will revolutionize study of radular structure and function. The 
data cited above represents only the very first glimpses of knowledge that can be obtained by use of this 
instrument. 



MALACOLOGIA, 1973, 14: 147-165 

PROC. FOURTH EUROP. MA LAC. CONGR. 

SCANNING ELECTRON MICROSCOPE STUDIES OF GASTROPOD RADULAE 

T. E. Thompson and A. Bebbington 

Zoology Department, University of Bristol, England 

INTRODUCTION 

Traditional methods of preparing the gastropod radula for microscopical examina- 
tion are well known. In a recently published variant of these, the radula is freed from 
the buccal mass by first boiling in caustic potash, washing with 70% alcohol, and then 
mounting flat on a microscope slide in polyvinyl lactophenol containing the stain 
lignin pink (Thompson, 1958). That publication included a photomicrograph probably 
showing the maximum that can be achieved by optical microscopy of small opistho- 
branch radulae. A photograph of part of the much larger radula of Aplysia as seen 
with the light microscope has been given by Bebbington & Thompson (1968). Most 
accounts of radulae, however, are restricted to drawings such as those given by 
Bebbington (1969) for Bursatella. 

The traditional methods of preparation are imperfect when one tries to understand 
the functional morphology of the opisthobranch radula, because it is necessary to 
squash the preparation. The results of squashes are unpredictable and can, moreover, 
distort or alter the natural relationships of the teeth. The scanning electron micro- 
scope (SEM) permits the examination and photography of radulae without elaborate 
preliminary preparation and without squashing or fragmentation. A clear picture of 
three-dimensional morphology can therefore be obtained which enlightens more mun- 
dane methods of observation. 

The principles on which the SEM is based have been described by Oatley, Nixon & 
Pease (1965). Runham & Thornton (1967) used the technique to examine the radulae 
of Patella vulgata and Agriolimax reticulatus . Thompson & Hinton (1968) described 
observations on some opisthobranch radulae: Aeolidia papulosa, Facelina auriculata, 
Archidoris stellifera and Cadlina laevis; and also on the shell sculpture of several 
species of Philine. Runham (1969), in the Proceedings of the Third European Mala- 
cological Congress, reported on the radulae of Agriolimax reticulatus and Nucella 
lapillus. Thompson (1972) in a paper on eastern Australian Pleurobranchomorpha 
showed the radular teeth of Berthellina citrina, Pleurobranchus peroni and Euselenops 
luniceps, and, more recently (Thompson, 1972), illustrated the radulae of Casella 
atromarginata and Chromodoris amoena. Solem(1970)ina review of the malacological 
applications of the SEM introduced pictures of some features of the shell surface. 
Recently, Robertson (1972) has used the SEM to study the shells of planktonic larval 
marine gastropods, and Bebbington (1972) has published photographs of the radulae 
and penial spines of Notar chus punctatus and Bursatella leachi savigniana. 

MATERIALS AND METHODS 

The specimens from which the radulae were obtained were collected from a number 
of localities in the United Kingdom; at Arcachon, France; from various marine sites 
in Queensland and New South Wales, Australia; from the Friday Harbor Laboratories, 
U.S.A.; from Naples, Italy, and from Kenya, East Africa. 

A total of 36 species have been examined in order to assess the value of the SEM for 
studies of gastropod radulae. Thirty-three of these were opisthobranchs, 2 were 

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148 PROC. FOURTH EUROP. MALAC. CONGR. 

prosobranchs and 1 was a pulmonate: 
Phylum Mollusca 
Class Gastropoda 
Sub-class Prosobranchia 
Order Neogastropoda 

Conns geographus (PI. 1), Conus marmoreus (PI. 2) 
Sub-class Opisthobranchia 
Order Bullomorpha 

Bullina lineata (PI. 3a,b), Haminea navícula, Hydatina physis (PI. 3c,d) 
Order Aplysiomorpha 

Aplysia párvula (PI. 4a,b), Aplysia dactylomela (PI. 4c,d), Aplysia depilans, 
Bursatella leachi leachi. (PI. 7d), Bursatella leachi savigniana, Dolabella 
auricularia (PI. 5a,b), Dolabrifera dolabrifera (PI. 6), Notarchus punctatus 
(PI. 7a,b), Stylocheilus longicauda (PI. 7c) 
Order Pleurobranchomorpha 

Berthellina citrina, Euselenops luniceps, Pleurobranchus peroni 
Order Sacoglossa 

Elysia bennetti (PI. 8a) 
Order Nudibranchia 

Sub-order Dendronotacea 

Dendronotus frondosus (PI. 9c,d) 
Sub-order Arminacea 

Armina californica (PI. 10) 
Sub-order Doridacea 

Casella atromarginata (PI. llc,d), Cadlina laevis, Chromodoris amoena 
(PI. 12a), Chromodoris loringi (PI. 12b), Hypselodoris bennetti, Hypselo- 
doris infucata (PI. 12d), Kalinga ornata (PI. 13), Onchidoris bilamellata 
(PI. 8b), Polycera capensis (PI. 14c, d), Rostanga arbutus (PI. lla,b), 
Triopha carpenteri (PI. 14a,b) 
Sub-order Aeolidacea 

Aeolidia papulosa, Facelina auriculata longicornis (PI. 9b), Hermissenda 
crassicornis (PI. 12c), Pteraeolidia semperi (PI. 9a) 
Sub -class Pulmonata 
Order Onchidiacea 

Onchidium damelii (PI. 5c, d) 
Material for the SEM was freed from the gastropod body by dissection of the buccal 
mass followed by boiling in caustic potash, washing with 70% alcohol; and then the 
r adula was dried, mounted on a metal stub with "Durafix", and finally coated with a 
thin layer of gold-palladium (Thompson & Hinton, 1968). The preparations were exa- 
mined using a Cambridge Stereoscan microscope kindly made available by the Long 
Ashton Research Station. Technical assistance from Mrs Elizabeth Parsons is 
gratefully acknowledged. The opportunity was taken to examine the visual effects of 
rotating and tilting the coated specimens so as to understand and anticipate the fore- 
shortening and other illusory effects which may bedevil the interpretation of SEM 
micrographs. 

CONCLUSIONS 

The scanning method is rapid and same -day photographs may be obtained from urgent 
material. The radula is not damaged in any way by the preparative or other techniques 
and may be subsequently re-examined in the SEM or even cleared and mounted in 
balsam or polyvinyl lactophenol for optical microscope study. 



THOMPSON and BEBBINGTON 149 

The specimen in the SEM can be rotated and tilted while under observation (Pis. 2, 
3, 10), and this helps enormously the building up of a three-dimensional appreciation 
of radular morphology. It also helps to avoid the pitfalls which can result from light- 
microscope observations made solely upon squashed specimens mounted on a glass 
slide. 

While observations with the higher magnifications of the SEM can be valuable, for 
instance to demonstrate the beading on .the fine subdivisions of the teeth of Rostanga 
arbutus (PI. lib), or the denticulated cutting faces of the Elysia bennetti radular teeth 
(PI. 8a), the greatest applicability of the technique to functional morphology (e.g., Pis. 
8b, 14) is evident in the low to medium range of magnification (x 40 up to x 400). 

The SEM can allow the discovery of new radular details. In the teeth of Conus geo- 
graphus (PI. 1) a series of pores set in amongst a row of lateral barbs probably 
correspond to the problematic exit-pores through which the granular cone-venom 
reaches the exterior. These are invisible with the light microscope, whatever method 
of preparation may be attempted. 

SEM montage -photographs permit a clear picture to be built up of the radular vari- 
ation within a taxon. For instance, we have been especially interested in the Aplysi- 
omorpha, many representative genera of which we have now investigated (Pis. 4, 5, 6, 
7). As Eales (1944) has pointed out, radular patterns change more rapidly during the 
course of evolution than deeply seated characters like the nervous system. Within 
the Aplysiidae the radula of the 2 genera in the Aplysiinae (Syphonota, Aplysia) 
resemble one another closely, with their wide multidenticulate median teeth and bi- 
serrate laterals (PI. 4). The Dolabellinae (Dolabella) have little resemblance to this 
type for the central tooth is narrow and reduced and the scythe-shaped laterals are 
without denticulations (PI. 5a,b). The 3 genera of the Dolabriferinae {Dolabrifera, 
Petalifera and Phyllaplysia) have, however, an easily recognisable type of radula 
with wide median teeth and two-pronged laterals with or without accessory denticles 
(pi. 6). The Notarchinae {Notarchus (PI. 7a,b), Stylocheilus (PI. 7c), Barnardaclesia, 
and Bursatella (PL 7d)) are an odd group, in which the wide multidenticulate median 
tooth resembles that of the Aplysiinae but the lateral teeth do not. In Notarchus (PI. 
7a,b) the laterals are unique in their symmetry and denticulated margins while, in 
the remaining genera of the Notarchinae, such teeth may be considered to be derived 
from the Dolabriferinae type with its two-pronged lateral. The outer laterals may be 
degraded and the outer prong may be greatly reduced, resulting in teeth each of which 
possesses a rather long single cusp with lateral denticles, a tooth-type characteristic 
of Stylocheilus (PI. 7c), Barnardaclesia and Bursatella (PI. 7d) but found in no other 
member of the Aplysiidae. 

Like most new techniques of observation, the results obtained from the SEM pose 
more questions than presently have been answered, in relation to the functional morph- 
ology of the radula. Two representative questions raised by the photographs presented 
here can be summarised thus: 

1) What is the adaptive significance of the narrow (often uniseriate) radula possessed 
by many opisthobranchs which feed upon coelenterates? Hermissenda crassicornis 
(PL 12c), Aeolidia papulosa (Thompson & Hinton 1968), Facelina auriculata (PL 9b) 
and Pteraeolidia semperi (PL 9a) all feed on coelenterates and possess stout jaws and 
a denticulate horseshoe-shaped tooth-type. Dendronotus frondosus attacks closely 
similar prey and the narrow radula of a large adult has the formula 40 x 10.1.10 (PL 
9c,d). Whatever the evolutionary pressures which have guided the ancestors of these 
forms towards radular narrowing they have, strangely, not acted similarly on the 
primitive dendronotacean nudibranch Tritonia hombe'rgi, which also feeds upon coe- 
lenterates (chiefly Alcyonium), but possesses, as well as stout cutting jaws, a broad 
radula of a primitive kind (Thompson, 1962). Plainly, observations like these pre- 



150 PROC. FOURTH EUROP. MALAC. CONGR. 

sented graphically in the form of SEM micrographs, can stimulate further research 
into the detailed functioning of the buccal mass and associated organs during the 
manipulation and ingestion of the prey in eolidiform and tritoniform nudibranchs. 

2) Why should radular morphology be so variable in the sponge-eating dorid nudi- 
branchs? Apart from the fact that the radula is usually broad in such forms, they 
have little in common so far as tooth-shape is concerned. This can be seen clearly 
in the micrographs (Pis. 11, 12, 13). In Chromodoris amoena (PI. 12a) the radula is 
broad, reaching a formula in a 26 mm adult specimen of 82 x 98.1.98; all the teeth are 
denticulate. Near the mid-line of the radula, where the vestigial median teeth are 
detectable, the denticles are not prominent and the principal cusp of each tooth is 
short and hooked. Towards the side of the radula, each tooth becomes long and slender 
and the denticles appear more functional. The extreme marginal teeth, however, are 
again squat and the principal cusp and the denticles are approximately equal in size. 
In Hypselodoris infucata (PI. 12d) the broad radula reaches a formula of 73 x 97Л.97 
(30 mm adult specimen). The teeth near the middle of the radula are hooked and 
deeply bifid. In extreme lateral teeth the cusps are rudimentary, but supplementary 
denticles could be detected along the hinder face of each tooth. In Casella atromargi- 
nata (PI. llc,d) the formula of a 50 mm specimen was 252 x 52.0.52. The most central 
teeth bear 4 or 5 denticulations on each side of the cusp but these are confined to the 
outside of succeeding teeth and are lacking in extreme laterals. In Kalinga ornata 
(PI. 13) the rather uniform teeth are erect, multifid hooks. Finally, in Rostanga 
arbutus (PI. lla,b), the broad radula (52 x 48.0.48 in a 9 mm specimen) consists of 
lateral teeth of a simple hooked type bearing a few small denticles while the marginal 
teeth are elongate and produced distally to form an erect cluster of fine beaded rods. 
All these species (and, of course, many more) are known to feed upon siliceous sponges. 
Why should animals with similar diets have such a variety of tooth morphology? 
Perhaps the diets, or the methods of manipulation and ingestion, are not so uniform 
as has been thought. 

SUMMARY 

The scanning electron microscope has been used by the authors to study the radulae 
of some 36 species of gastropod molluscs of which 24 species are illustrated in the 
present paper. The usefulness of the scanning electron microscope in such studies 
is discussed together with some conclusions and questions raised by the information 
gained. 

REFERENCES 

BEBBINGTON, A., 1969, Bursatella leachi guineensis subsp. nov. (Gastropoda, Opis- 
thobranchia) from Ghana. Proc. malacol. Soc. Lond., 38(4): 323-341. 

BEBBINGTON, A., 1972, Aplysiid species from Malta with notes on the Mediterranean 
Aplysiomorpha (Gastropoda, Opisthobranchia). Pubbl. Sta. zool. Napoli, 38: 15-46. 

BEBBINGTON, A. & THOMPSON, T. E., 1968, Note sur les opisthobranches du Bassin 
d'Arcachon. Act. Soc. linn. Bordeaux, 105(5): 1-35. 

EALES, N. В., 1944, Aplysiids from the Indian Ocean with a review of the family 
Aplysiidae. Proc. malacol. Soc. Lond., 26: 1-22. 

OATLEY, C. W., NIXON, W. C. & PEASE, R. F. W., 1965, Scanning electron micro- 
scopy. Adv. Electronics Electron Phys., 21: 181-247. 

ROBERTSON, R., 1971, Scanning electron microscopy of planktonic larval marine 
gastropod shells. Veliger, 14(1): 1-12. 

RUNHAM, N. W., 1969, The use of the scanning electron microscope in the study of 



THOMPSON and BEBBINGTON 151 

gastropod radula: The radulae of Agriolimax reticulatus and Nucella lapillus 
Malacologia, 9(1): 179-185. 

RUNHAM, N. W. & THORNTON, P. R., 1967, Mechanical wear of the gastropod radula: 
a scanning electron microscope study. J. Zool. Lond., 153: 445-452. 

SOLEM, A., 1970, Malacological applications of scanning electron microscopy. I. 
Introduction and shell surface features. Veliger, 12(4): 394-400. 

THOMPSON, T. E., 1958, Observations on the radula of Adalaria próxima (A. & H.) 
(Gastropoda, Opisthobranchia). Proc. malacol. Soc. Lond., 33: 45-56. 

THOMPSON, T. E., 1962, Studies on the ontogeny of Tritonia hombergi Cuvier (Gastro- 
poda, Opisthobranchia). Phil. Trans. Roy. Soc, Lond., Ser. В, 245: 171-218. 

THOMPSON, T. E., 1970, Eastern Australian Pleurobranchomorpha (Gastropoda, 
Opisthobranchia). J. Zool. Lond., 160: 173-198. 

THOMPSON, T. E., 1972, Chromodorid nudibranchs from Eastern Australia (Gastro- 
poda, Opisthobranchia). J. Zool. Lond., 166: 391-409. 

THOMPSON, T. E. & HTNTON, H. E., 1968, Stereoscan electron microscope obser- 
vations on opisthobranch radulae and shell -sculpture. Bijdr. Dierk., 38: 91-92. 

ADDENDUM 

Since this paper was prepared, 3 important articles on radular fine structure have 
appeared. Kohn, Nybakken & Van Mol (1972) investigated the tooth of the vermivorous 
toxoglossan Conus imperialis, in which the tooth unit consists of an enrolled chitinous 
tube, very different from our interpretation of С geographus and C. marmóreas. 
Thiriot-Quiêvreux (1973) studied the taenioglossan radulae of various planktonic 
heteropods and her paper includes some electron micrographs of high quality and great 
usefulness to students of the group. Finally, Solem (1973), who studied pulmonate 
radulae from snails of the Charopidae, Enidae and Partulidae, has shown that patterns 
of interlock between radular teeth in adjacent rows are present, and his SEM studies 
have enabled him to propose that evolutionary convergence in cusp form has occurred 
in the Enidae and Partulidae. 

REFERENCES 

KOHN, A. J., NYBAKKEN, J. W. & VAN MOL, J. -J., 1972, Radula tooth structure of 

the gastropod Conus imperialis elucidated by scanning electron microscopy. 

Science, 176: 49-51. 
SOLEM, A., 1973, Convergence in pulmonate radulae. Veliger, 15(3): 165-171. 
THIRIOT-QUIEVREUX, C, 1973, Observations de la radula des Hétéropodes (Mollusca 

Prosobranchia) au microscope électronique à balayage et interprétation fonctio- 

nelle. C. r. Acad. Sei. Paris, 276: 761-764. 



152 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 1. Conus geographus, tooth of an adult cone from Great Barrier Reef, June 1968, show- 
ing in a, various barbs, and in b, fine barbs and associated venom exit-pores. 



THOMPSON and BEBBINGTON 



153 




PLATE 2. Conus marmoreus, tooth of an adult cone from the Great Barrier Reef, June 1968, 
showing, a and b, different aspects resulting from specimen-rotation in the SEM. 



154 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 3. aandb, Bullina Uneata, shell-length 13 mm, Long Reef, N. S. W. , Australia, May 
1968, showing the effect of specimen- rotation in the SEM; с and d, Hydatina physis, shell-length 
22 mm, from the same locality, showing how specimen-tilt in the SEM can alter the apparent 
aspect of the radular teeth. 



THOMPSON and BEBBINGTON 



155 







PLATE 4. a and b, Aplysia párvula, weight 5. 3 g (in alcohol), Sydney Harbour, N. S. W. , Aus- 
tralia, February 1968; с and d, Aplysia dactylomela, weight 180 g (in alcohol), from the same 
locality, March 1968. 



156 



PROC. FOURTH EUROP. MALAC. CONGR. 








PLATE 5. a and b, Dolabella auricularia, weight 25. 1 g (in alcohol), Moretón Bay, Queensland, 
Australia, July 1968; с and d, Onchidium damelii, length 3 cm (in alcohol), Pitt Water, N. S. W., 
Australia, April 1968. 



THOMPSON and BEBBINGTON 



157 




PLATE 6. aandb, Dolabrifera dolabrifera, weight 2.2 g (in alcohol), Kenya, East Africa, 
August 1970; с and d, D. dolabrifera, weight 18.1 g (in alcohol), Long Reef, N. S. W., Australia, 
February 1968. 



158 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 7. a and b, Notarchus punctatus, weight 7. 8 g (in alcohol), Naples, Italy, 1970; c, 
Stylocheilus longicauda, weight 0.09 g (in alcohol), Johnson's Reef, Eastern Australia, January 
1963; d, Bursatella leachi leachi, weight 40 g (in alcohol), Myora, Queensland, Australia, June 
1968. 



THOMPSON and BEBBINGTON 



159 




PLATE 8. a, Elysia bennetti, length 25 mm (in alcohol), Great Barrier Reef, June 1970; b, 
Onchidoris bilamellata, length 26mm (in alcohol), Helford Passage, Cornwall, U.K., March 
1971. 



160 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 9. a, Pteraeolidia semperi, adult from Botany Bay, N. S.W. , Australia, March 1968; 
b, Facelina auriculata longicomis, length 3 cm alive, Falmouth Cornwall, U.K. (photograph by 
H. E. Hinton, F.R. S. ); с and d, Dendronotus frondosus , adult from Plymouth, Devon, U.K., 
June 1971. 



THOMPSON and BEBBINGTON 



161 




PLATE 10. a-d, Armina califontica, length 6 cm (in alcohol), dredged off the San Juan Islands, 
U. S.A., August 1969, shewing the apparent effects of altering the SEM specimen-tilt mechanism. 



162 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 11. a and b, Rostanga arbutus, length 8 mm alive, Long Reef, N. S. W., Australia, Feb- 
ruary 1968; с and d, Casella atromarginata, adult from Botany Bay, N.S.W., Australia, March 
1968. 



THOMPSON and BEBBINGTON 



163 




PLATE 12. a, Chromodoris amoena, length 26 mm (in alcohol), Botany Bay, N.S. W. , Australia, 
March 1968; b, C. loringi, adult, from the same locality; c, Hermissenda crassicomis, length 
45mm, San Juan Island, U.S.A., June 1969; d, Hypselodoris infucata, adult from Myora, 
Queensland, Australia, June 1968. 



164 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 13. a, Kalinga ornata, length 45 mm (in alcohol), S. E. Queensland, Australia, Decem- 
ber 1937; b, K. ornata, length 60 mm (in alcohol), from the same locality. 



THOMPSON and BEBBINGTON 



165 




PLATE 14. a and b, Triopha carpenteri, length 9 cm alive, dredged off the San Juan Islands , 
U.S.A. , July 1969; с and d, Polycera capensis, length 3 cm alive, Sydney Harbour, N. S.W. , 
Australia, March 1968. 



MALACOLOGIA, 1973, 14: 166 

PROC. FOURTH EUROP. MALAC. CONGR. 
THE RADULA OF THE CHAETODERMATIDAE (APLACOPHORA, CHAETODERMATIDA) 

Amélie H. Scheltema 
Woods Hole Océanographie Institution, Woods Hole, Massachusetts, U.S.A. 

ABSTRACT 

The aplacophoran family Chaetodermatidae (genera Falcidens and Chaetoderma) has a radula consisting 
of a single cone-shaped structure in connection with a pair of teeth. The genus Falcidens has, as well, a 
plate with 2 extensions that wrap around the paired teeth. 

One species of each genus is known to feed on foraminifera. 

The buccal mass bears many similarities to the gastropod buccal mass: it is covered distally by a sub- 
radular membrane connected to the radula; it lies in a buccal cavity; it contains a pair of bolsters, from 
which run muscles to the radula and subradular membrane; it has a blood sinus surrounding a sac of 
epithelial cells which secrete the cone-shaped tooth. 

This sac is considered to be a radula gland homologous to that of other mollusks. It lies between and 
above the bolsters, as in other mollusks. At its proximal, blind end are 4 large odontoblasts. 

The cone-shaped tooth is considered to be a fused, permanent, continuously secreted radula. Scanning 
electron photomicrographs support this view. 



(166) 



MALACOLOGIA, 1973, 14: 167-206 

PROC. FOURTH EUROP. MALAC. CONGR. 

EUTHYNEURAN AND OTHER MOLLUSCAN SPERMATOZOA 

T. E. Thompson 

Zoology Department, University of Bristol, U.K. 

ABSTRACT 

Spermatozoa of Euthyneura possess a variable number of spiral structures 
along the tail. These were investigated using both conventional methods of pre- 
paration for electron microscopy and freeze-etching techniques. Spermatozoa 
of Acteon possessed 4 distinct mitochondrial spiral keels, those of Aplysia and 
Bursatella had only 2, while in the nudibranchs only 1 keel was detectable. 

The situation in the pulmonates is variable, the arrangement in the Stylom- 
matophora investigated being similar to the nudibranchs , while the Basomma- 
tophora investigated possessed a multiplicity of helical structures in the sperm- 
tail. 

CONTENTS 

INTRODUCTION 168 

MATERIALS AND METHODS 170 

GENERAL CHARACTERISTICS OF MOLLUSCAN SPERMATOZOA 171 

EUTHYNEURAN SPERMATOZOA 182 

A. BULLOMORPHA {Acteon tornatilis, Bulla ampulla, Hydatina 

physis, Haminea virescens) 182 

B. PYRAMIDELLOMORPHA (Odostomia columbianus, Odostomia sp. ) 183 

C. PLEUROBRANCHOMORPHA (Umbraculum sinicum, Pleurobranchus 

peroni, Berthella plumula) 184 

D. APLYSIOMORPHA (Aplysia spp. , Dolabella auricularia, Dolabrifera 

dolabrifera, Bursatella leachi, Phyllaplysia taylori) 185 

E. NUDIBRANCHIA (Archidoris pseudoargus, Tritonia festiva, 

Dendronotus iris, Cadlina laevis, Hermissenda crassicornis, 

Armina californica) 185 

F. PULMONATA (Planorbarius corneus, Physa gyrinus, Physa 

fontinalis,Lymnaea peregra, L. stagnalis, Achatina fúlica, Helix 
pomatia, Onchidium damelii, Áriolimax columbianus, Hedleyella 
falconeri) 186 

CONCLUSIONS I 88 

ACKNOWLEDGEMENTS I 88 

ABBREVIATIONS USED IN THE ILLUSTRATIONS 204 

REFERENCES 204 



(167) 



168 PROC. FOURTH EUROP. MALAC. CONGR. 

INTRODUCTION 

Serious interest in molluscan spermatozoa began with the publication in 1906 of 
Retzius's splendid monograph, in which he described and illustrated the structure 
(using bright -field optical microscopy) of the gametes of numerous molluscs. These 
pioneering studies have often been ignored by later workers. One example of this 
was documented by Thompson & Bebbington (1970) in reviewing different published 
interpretations of the structure of the complex aplysiid spermatozoon. Both Tuzet 
(1940) and Franzén (1955) ignored Retzius's description of this type of gamete in their 
published reviews, yet the electron microscope shows (Thompson & Bebbington, 1969) 
that Retzius had in fact provided a description no less accurate than those of later 
light-microscopists. Retzius's microscopical investigations without doubt represent 
the highest possible level of achievement in optical studies of live metazoan sperma- 
tozoa. Fortunately, modern techniques of fine -structure investigation have resulted 
in methods such that we do not have to be as skilled as Retzius to achieve worthwhile 
results. Standard techniques of transmission electron microscopy, which can be 
learnt and applied by a novice after a short period of training, enable the research 
worker to go deeply into details of cell substructure that the optical microscopists 
could only guess at. New methods of preparation for electron microscopy, such as 
freeze-etching, allow the investigator to have the advantage of a physical (not chemical) 
technique of fixation, especially useful in studies of complex cells like spermatozoa 
(Koehler, 1970; Thompson, 1971). Finally, and most important of all, the application 
of techniques of ultrastructural cytochemistry with great brilliance by André, Personne 
& Anderson (key references listed by Personne & Anderson, 1970) has enabled a 
serious start to be made in understanding the functioning of various parts of the 
spermatozoan body. It may be added that the application of certain techniques of simple 
physics to the study of scale-models of molluscan spermatozoa has proved to be 
rewarding in trying to understand the functional morphology of euthyneuran gametes 
(Thompson, 1966). 

The principal conclusions to be drawn from Retzius's survey of molluscan sperma- 
tozoa were that there was considerable heterogeneity in shape and size; that all the 
normal (i.e., fertilizing or eupyrene) gametes were capable of motility; that helical 
modifications of acrosome, nucleus, and principal-piece were encountered in many 
species; and that the spermatozoa of the primitive groups (such as bivalves and chi- 
tons), with external fertilization, were apparently less specialized morphologically 
than those of the more advanced, internally fertilizing groups (such as the higher 
gastropods). 

Franzén (1955) investigated a greater variety of molluscan spermatozoa and fully 
established these conclusions. His paper is a model of patience and thoroughness and 
he clearly showed that, to use his own words, "the morphology of the sperm within 
the Mollusca can be said to stand in a certain relation to the biology of fertilization. 
The primitive type of sperm is retained in forms which discharge their sperms freely 
into the water. In the cases where an internal fertilization takes place or where the 
sperms are delivered in the immediate vicinity of the female genital opening, the 
sperm differs morphologically more or less from the primitive type." These morpho- 
logical modifications chiefly affect the head and the middle piece and are "obviously 
connected with the different nature of the medium at the place where the sperm is in 
quest of the egg." 

Other workers have contributed towards the understanding of the structure and 
functioning of the sub-cellular constituents of the advanced spermatozoon of the Opistho- 
branchia (Thompson, 1966; Thompson & Bebbington, 1969, 1970; Thompson, 1971) and 
in the Prosobranchia and Pulmonata (reviewed by Personne & Anderson, 1970, and by 



THOMPSON 169 

Favard & André, 1970). Many of these publications have included observations on 
spermiogenesis, invaluable in attempts to define the homology of the spermatozoan 
organelles throughout the Mollusca. According to Favard & André (1970) the changes 
which occur in the spermatid mitochondria during spermiogenesis in the pulmonates 
represent the most extreme mitochondrial transformation and re -modelling yet 
detected in animal gametes. The mitochondria of the young spermatid assemble around 
the centriolar cone to the rear of the nucleus, before fusing to form a continuous 
sheath which extends rearward, enveloping the flagellum. In this very complete 
fusion of mitochondrial elements, the matrices of the cristae and both internal and 
external membranes all merge. Most of the bulk of this large mitochondrial deriva- 
tive (which may come to occupy about 95% of the volume of the spermatozoon) is made 
up of a proteinaceous crystal composed of particles 90Á in diameter. According to 
Favard & André (1970) this crystal is traversed by 2 or more helically coiled canals 
of 2 different kinds. One of these they term the major helix (Andre, 1962) and this 
type is filled with glycogen during the last phase of spermiogenesis (Personne & André, 
1964). The other type is the secondary helix and is derived from the matrix areas of 
the original mitochondrion. Using cytochemical methods Favard & André report 
findings showing Krebs cycle activities in the secondary helix, cytochrome activities 
in the body of the crystal, and Phosphorylase activity in the major helix (based upon 
photographs supplied by Anderson & Personne). These results appear to be derived 
entirely from studies of the stylommatophoran Helix. There is known to be consider- 
able morphological diversity in euthyneuran spermatozoa. For instance, in Planorbis 
there are known to be 2 major helices, compared with 1 in Helix. In Planorbis both 
of these are known to contain glycogen (Personne & Anderson, 1970). In Testacella 
there are 3 helices: 1 is a glycogen canal and the others contain condensed matrix 
material (Andre, 1959). 

After an exhaustive investigation into spermiogenesis in the pulmonate Succinea, 
Hickmann (1931) concluded that: "concerning the functional significance of the spiral 
arrangement of the sperm of pulmonates we are very much in the dark." Thanks to 
the work of André, Anderson and Personne, we now know that these spirals are con- 
nected with the provision of substrates for the metabolism of the flagellar axoneme. 
But this explanation raises more questions. Why should the configuration of these 
materials be a spiral one? Why should the spiralling components of the mitochondrial 
derivatives stand out as prominent ridges upon the surface of the sperm tail? Are 
these mitochondrial helices related geometrically and functionally to the spiral struc- 
tures often distinguishable on the head of various spermatozoa among the higher 
molluscs? In a paper published in 1966, I proposed that a simple answer could be 
offered to these questions. This proposal came out of an investigation into the loco- 
motion of active allosperms of the opisthobranch Archidoris pseudoargus by means of 
ciné-photomicrographic techniques. It will be necessary at this point to summarize 
some of the results obtained. During swimming, thrust was provided by flagellation 
of the kind described by Gray (1955, 1958) in echinoid and mammalian spermatozoa, 
with a series of propagated waves originating in the neck and progressing down the 
tail. So far as could be ascertained, the waves originating in the sperm-neck are 
uniplanar and approximately symmetrical on the 2 sides. (In abnormally moving 
individual spermatozoa, encountered occasionally, the waves originate at the rear and 
pass forwards, resulting in sperm-progression backwards). As normal Archidoris 
allosperms progress forwards they spin in a clockwise direction when viewed from 
the front. This spinning may exceed 8 rev/s. As a sperm moves forward the spinning 
spiral mitochondrial keel (of which there is only 1 in nudibranchs such as Archidoris) 
gives rise to the illusion of short-period waves passing backwards along the tail 
(similar to the waves apparent on a rotating barber's pole). In the abnormal individuals 



170 PROC. FOURTH EUROP. MALAC. CONGR. 

referred to above this is reversed. 

It seemed likely that the spinning of motile spermatozoa of Archidoris is brought 
about by the spiral mitochondrial keel and the spiral shape of the head itself, through 
their differential alterations of the moving spermatozoon's resistance to torque. To 
test whether such a keel could function in this way a preliminary glass model was 
constructed to scale and towed in water. This was found to spin so long as forward 
motion continued, and, in short, reproduced some of the features of normal spermato- 
zoan motility. This was of indefinable significance, however, because of the disparity 
between the Reynolds number of the spermatozoon/seminal fluid and the glass model/ 
tap-water systems. To obtain further evidence, a number of models were constructed 
more accurately, using nylon thread and glass, and these were towed at 5 cm/h through 
glycerol at temperatures ranging from 5 to 19°C. In these experiments the Reynolds 
number was found to be acceptably close to that calculated for the natural system. In 
the trials, the sperm model when in motion rotated (up to 1 l/2 spins/h) upon its long 
axis in a clockwise direction when viewed from the front, thus giving experimental 
support for the hypothesis advanced above. What appears to be true for spermatozoa 
of Archidoris may well apply more widely to other euthyneurans with external helical 
keel-like modifications, namely that such structures by their differential alteration 
of the moving gamete's resistance to torque convert uniplanar flagellation into helical 
progression of the spermatozoon. The advantages of spinning progression are uncer- 
tain. It may allow faster progression in the female tract; it may even facilitate oocyte- 
penetration during the process of fertilization in vivo. 

A number of other issues have emerged following recent studies of various molluscan 
gametes. Stringer (1963) in attempting to use sperm-morphology as a guide to phylo- 
genetic affinity, stated that the "spiral form of the spermatozoa" is found only in the 
pulmonate gastropods. This is certainly untrue, and leads to the. conclusion that 
guidelines are needed to help students of molluscan evolution to use information about 
spermatozoa wisely. Bayne (1970) investigated the fine -structure of spermatozoa of the 
slug Agriolimax reticulatus and found the axoneme to consist of a 9 + 2 arrangement 
but the 9 outer moieties were single, not double as in typical metazoan flagella, whereas 
other workers (summarized by Giusti, 1969) have reported a 9 + 9 + 2 axoneme and 
have described a fibres of the doublet type. Clearly, this is a field where further 
study is needed. Another problem demanding fine-structural study is the claim, by 
Martin et al. (1970), that spermatozoan heads of Octopus dofleini possess superfi- 
cially disposed sheaths of glycogen. These are the kinds of issues that have stimu- 
lated the present investigations, but it is certainly not yet possible, regrettably, to give 
more than partial answers to some of the questions that they raise. 

The present paper reports on my work on various molluscan spermatozoa, in an 
effort to synthesize the known extraordinarily wide range of gamete morphology in 
the phylum, as well as to explore some new techniques of examination of small cells 
and sub-cellular structures. 

MATERIALS AND METHODS 

Living spermatozoa were examined by various methods of optical microscopy, 
sometimes after vital dyeing with neutral red or janus green. Most of the routine 
work was carried out using a Wild Mil phase-contrast microscope (PI. 1A). Fluor- 
escence microscopy after staining with acridine orange was useful in distinguishing 
the acrosome in difficult material. Zeiss interference microscopy was excellent for 
studying fine helical structures on the head in living spermatozoa, but the more simple 
Zeiss Nomarski microscope is little inferior in performance using such cells (PI. 1B- 
D). Straightforward bright -field optical microscopy is poor for the study of small 



THOMPSON 171 

cells such as molluscan gametes and it is a matter for surprise and admiration that 
the early work of Retzius (1906) was carried out solely by this method. Considerable 
insight into the structure of fresh gametes could be obtained by allowing them to dry 
out gradually, in a bubble of air trapped beneath a conventional cover-glass, while a 
close watch was kept upon the changes which began after cell-death. The nucleus 
frequently bursts rather readily in such pathological preparations, enabling a close 
scrutiny to be made of the more robust acrosome and centriolar cone. The advantages 
of some of these techniques can be compared in Plate 1. The nucleus itself could be 
characterized and studied best after fixation of a gamete-smear on a glass slide in 
the vapour of acetic acid and staining in haemalum or any other standard nuclear dye. 

Material for the electron microscope was sometimes examined whole, sometimes 
sectioned in Araldite, and sometimes processed by the freeze-etching method. A) 
Whole mount preparations were made by allowing living gametes to dry down on a 
copper grid, in an atmosphere saturated with the vapour of either osmic acid or 
formaldehyde. After 3 hours the grid was washed in distilled water, dried and exa- 
mined. The micrographs obtained (PI. 2) show gamete silhouettes but occasionally 
surface or internal details can be discerned by careful focusing of the microscope 
(PI. 2C, F, G) and adjustment of photographic exposures. B) Material for sectioning 
was fixed in phosphate-buffered 25% glutaraldehyde with added sucrose, washed in 
the buffer, then post -fixed in 1% osmic acid in the buffer. Araldite sections were 
stained with saturated uranyl acetate in 70% alcohol. C) Existing methods (such as 
those outlined above) for investigating the spatial relationships at the ultrastructural 
levels of cells and of sub-cellular structures have at least 2 disadvantages. 1) Chemi- 
cal fixation results in unpredictable, sometimes capricious damage to the specimen. 
2) Cytological three-dimensional reconstruction is difficult even when serial sectioning 
has been mastered. The technique of freeze-etching, devised by Steere (1957) and 
refined by Moor (1964) as an adjunct to transmission electron microscopy of biological 
and medical materials, offers a helpful alternative to the older preparative methods. 
Moor's technique is novel in that it is a purely physical preparation of the specimen, 
thus providing a useful check on preparative methods which involve chemical fixation. 
Considerations of space preclude a detailed account of the freeze-etching method and 
the interested reader is referred to my paper on the application to molluscan ultra- 
structure research of the Balzers 360M freeze-etching plant (Thompson, 1971). Elec- 
tron micrographs obtained in this way (Pis. 3C, 11-14) have a three-dimensional 
quality which is strikingly reminiscent of micrographs from the scanning electron 
microscope (Thompson & Hinton, 1968) but of course far better resolution can be 
obtained using a transmission electron microscope. This three-dimensional appear- 
ance is not spurious, and genuinely allows a rapid, accurate appreciation of spatial 
relationships. Some of the micrographs presented here illustrate this point. They 
enable an immediate understanding of the shape of some of the components of the 
euthyneuran sperm-tail. It can be exceedingly laborious to build up such a clear pic- 
ture of this kind of cell by reconstruction of serial sections. The only insurmountable 
defect of the freeze-etching method at present is the fact that certain organelles do 
not survive the preparation well. The a and ß fibrils of flagella, for instance, become 
difficult to discern. 

The live animals studied were obtained in Bristol or during working visits to 
laboratories in Australia, Britain, France and the U.S.A. Table 1 lists the species 
examined, their source, and the principal methods of investigation. 

GENERAL CHARACTERISTICS OF MOLLUSCAN SPERMATOZOA 

Molluscan male gametes are all elongated motile cells. In most species the fully 
mature spermatozoa are morphologically uniform but in certain prosobranch gastro- 



172 



PROC. FOURTH EUROP. MALAC. CONGR. 
TABLE 1. Material 









Whole 


Sectioned 








Examined 


mount 


for 


Freeze- 


Species 


Source* 


optically** 


electron 
micros с opy+ 


electron 
microscopy" 44 " 


etched'*' 


Acanthochitona crinitus 


Arcachon 


X 


X 






Transennella tantilla 


Friday Harbor 


X 








Gibbula cineraria 


Plymouth 


X 


X 






Gibbula umbilicalis 


Plymouth 


X 








Acteon tornatilis 


Rhossili 


X 


X 


X 




Bulla ampulla 


Myora 


X 


X 


X 




Hydatina pkysis 


Long Reef 


X 


X 






Haminea virescens 


Friday Harbor 


X 








Odostomia columbianus 


Friday Harbor 


X 


X 






Odostomia sp. 


Friday Harbor 


X 


X 


X 




Dolabella auricularia 


Myora 


X 








Dolabrifera dolabrifera 


Long Reef 


X 


X 


X 




Bur sat ella leachi 


Myora 


X 


X 






Phyllaplysia taylori 


Friday Harbor 


X 


X 






Aplysia punctata 


Plymouth 


X 


X 


X 


X 


Aplysia depilans 


Arcachon 


X 


X 


X 


X 


Umbraculum sinicum 


Long Reef 


X 


X 


X 




Pleurobranchus peroni 


Long Reef 


X 


X 


X 




Berthella plumula 


Plymouth 


X 


X 


X 




Tritonia festiva 


Friday Harbor 


X 


X 






Dendronotus iris 


Friday Harbor 


X 


X 






Archidoris pseudoargus 


Cornwall 


X 


X 


X 


X 


Cadlina laevis 


Cullercoats 


X 


X 






Hermissenda crassicornis 


Friday Harbor 


X 


X 






Armina califomica 


Friday Harbor 


X 


X 






Planorbarius corneus 


Bristol 


X 


X 




X 


Lymnaea peregra 


Bristol 


X 


X 


X 


X 


Lymnaea stagnalis 


Bristol 


X 


X 




X 


Physa fontinalis 


Bristol 


X 


X 




X 


Physa gyrinus 


Bristol 


X 








Hedleyella falconeri 


Queensland 


X 


X 






Onchidium damelii 


Pitt Water 


X 


X 


X 




Helix aspersa 


Bristol 


X 


X 






Helix pomatia 


Bristol 


X 


X 




X 


Ariolimax columbianus 


Friday Harbor 


X 


X 






Loligo opalescens 


Friday Harbor 


X 


X 







♦Plymouth Sound, Cornwall, Bristol, Cullercoats, Rhossili in U. K. ; Arcachon in France; 
Friday Harbor, U.S.A.; Myora in Queensland, Long Reef and Pitt Water in N. S. W. , 
Australia. 

**Wild Mil phase microscope; Zeiss Nomarski photomicroscope. 

+Dried in OS2O4 or HC HO vapour. 
++Fixed in buffered glutaraldehyde ; postfixed in OS2O4. 

t Method described by Thompson, 1971. 



THOMPSON 



173 



AcTEON TORNATILIS 




5jjm 

FIG. 1. Spermatozoon of Acteon tomatilis . 

GlBBULA CINERARIA TrANSENNELLA TANTILLA 



LOLIGO OPALESCENS 




3 




FIG. 2. Spermatozoa of Gibbula cineraria, Transennella tantilla and Loligo opalescens. 



174 PROC. FOURTH EUROP. MALAC. CONGR. 

HamiNEA VIRE5ŒNS ODOSTOMIA C0LUMBIANU5 ODOSTOMIA 5K 



i 



FIG. 3. Spermatozoa of Haminea virescens, Odostomia columbianus and Odostomia sp. 
Umbraculum sinicum 




FIG. 4. Spermatozoon of Umbraculum sinicum 



Pleurobranchus peroni 



THOMPSON 

Bulla ampulla 



Hydatina physis 



175 







J 



FIG. 5. Spermatozoa of Pleurobranchus peroni, Bulla ampulla and Hydatina physis. 
Aplysia SPP. 




FIG. 6. Spermatozoon of Aplysia spp. 



176 



PROC. FOURTH EUROP. MALAC. CONGR. 
Archidoris pseudoargus 




FIG. 7. Spermatozoon of Archidoris pseudoargus. 

Cadlina laevis Tritonia festiva 



Dendronotus iris 



-fc 

3 



(3 

3 






FIG. 8. Spermatozoa of Cadlina laevis, Tritonia festiva and Dendronotus iris. 



THOMPSON 



177 



^RMINA CALIFORNICA 



Her 



FIG. 9. Spermatozoa of Armina califomica and Hermissenda crassicornis. 
Heoleyella falconeri Planorbarius corneus 




>ms 




20yum 



FIG. 10. Spermatozoa of H edley ella falconeri and Planorbarius corneus. 



20)лт\ 



178 



PROC. FOURTH EUROP. MALAC. CONGR. 



Helix pomatia 



L.YMNAEA 5TAGNALIS 



Ariolimax columbianus 



_pmd 



smd 



; pmd 



FIG. 11. Spermatozoa of Helix pomatia, Lymnaea stagnalis and Ariolimax columbianus . 



pods dimorphism occurs. The normal kind of gamete is then said to be eupyrene, 
while the novel kind is incapable of participating in egg-penetration or in amphimixis, 
and, being virtually devoid of nuclear chromatin, is said to be oligopyrene or apyrene. 
Details of the structure and functioning of these atypical spermatozoa are outside the 
scope of the present paper; the subject has been reviewed by Nishiwaki (1964) and by 
Hyman (1967). Throughout the present paper the term spermatozoon refers only to 
eupyrene gametes. 

Table 2 shows the sizes of spermatozoa of various molluscs. It is often axiomatic 
in discussions of gamete size to stress that the male or micro-gamete is always much 
smaller than the female or mega-gamete, and this is of course true, but only in terms 
of biomass. If linear dimensions are compared it is often found that sperm-length 
greatly exceeds ovum-diameter. The smallest molluscan spermatozoa are those of 
chitons, bivalves, and, perhaps surprisingly, cephalopods (with the exception of the 
500 fim long gametes of the giant North Pacific Octopus dofleini). In most of these 
forms there is no clear correlation between adult-size and sperm-size. On the other 
hand, within the pulmonate gastropods considerable evidence exists that the largest 
species do predictably possess the longest spermatozoa. The largest sperm so far 
reported for any mollusc occurs in the giant Queensland forest snail Hedleyello 
falconeri (Fig. 10). Perhaps this apparent positive correlation will prove to be 
spurious; all that will be needed will be the discovery of several species of small 
pulmonates which possess spermatozoa more than 1 mm in length. 

The basic type of spermatozoon found in the Mollusca (Franzén, 1955) is possessed 
by externally fertilizing species such as the gastropod Gibbula cineraria (Pis. 2A, 5; 
Fig. 2) (see also the excellent paper of Personne & Anderson, 1970). The length 
overall was approximately 60 /um. The head of a freshly-shed spermatozoon measured 



THOMPSON 

TABLE 2. Size of molluscan spermatozoa. 



179 



Species 



Acanthochitona crinitus 
Lepidopleurus asellus 
Lepidochitona cinerea 
С ha et od er ma nitidulum 
Nucula sulcata 
Crassostrea virginica 
Unio pictorum 
Thracia papyracea 
Transennella tantüla 
Gibbula umbilicalis 
Gibbula cineraria 
Hydrobia ulvae 
Onoba striata 
Turritella communis 
Caecum glabrum 
Triphora perversa 
Velutina velutina 
Pomatias elegans 
Nassa reticulata 
Acteon tornatilis 
Diapha?ia minuta 
Cylichna cylindracea 
Bulla ampulla 
Hydatina physis 
Odostomia columbianus 
Odostomia sp. 
Haminea navícula 
Haminea vires с ens 
Akera bullata 
Dolabella auricularia 
Dolabrifera dolabrifera 
Aplysia depilans 
Aplysia fasciata 
Aplysia punctata 
Bursatella leachi 
Umbraculum sinicum 
Pleur obranchus peroni 
Berthella plumula 
Tritonia hombergi 
Tritonia festiva 
Dendronotus iris 
Archidoris pseudoargus 
Onchidoris muricata 
Armina californica 
Hermissenda crassicornis 
Planorbarius corneus 
Lymnaea stagnalis 
Lymnaea peregra 
Onchidium damelii 
Succinea ovalis 



Length in ¡xm 



65 

79 

33 

90 

58 

40 

39 

64 

66 

50 

60 

100 

140 

115 

120 

140 

90 

135 

150 

230 

215 

200 

106-115 

155 

250 

750-876 

240 

264-270 

260 

275 

350 

155-158 

182-185 

215-228 

180 

225 

180-190 

440 

280 

180-190 

288 
208-210 

300 
222-228 
204-210 
720 
690 
550 
420 
420 



Source 


(P - Present 


Paper) 


P 




Franz en, 


1955 


P 




Franz en, 


1955 


Franz en, 


1955 


Galtsoff & Philpott, 1960 


Franzen, 


1955 


Franzen, 


1955 


P 




P 




P 




Franzen, 


1955 


Franzen, 


1955 


Franzen, 


1955 


Franzen, 


1955 


Franzen, 


1955 


Franzen, 


1955 


P 




Franzen, 


1955 


P 




Franzen, 


1955 


Franzen, 


1955 


P 




P 




P 




P 





Dupouy, 1960 

P 

Franzen, 1955 

P 

P 

Thompson & Bebbington, 1969 

Thompson & Bebbington, 1969 

Thompson & Bebbington, 1969 

P 

P 

P 

P 

Thompson, 1961 

P 

P 

Thompson, 1966 

Franzen, 1955 

P 

P 

P 

P 

P 

P 

Hickman, 1931 



180 PROC. FOURTH EUROP. MALAC. CONGR. 

Table 2 (Continued) 







Source 


Species 


Length in \im 


(P - Present Paper) 


Hedleyella falconeri 


1140-1400 


P 


Physa fontinalis 


375 


P 


Physa gyrinus 


350 


P 


Achatina fúlica 


750 


P 


Helix aspersa 


655 


P 


Helix pomatia 


850 


P 


Ariolimax columbianus 


265 


P 


Eledone moschata 


195 


Franzén, 1967 


Loligo forbesi 


69 


Franzén, 1955 


Loligo pealii 


50 


Austin et al. , 1964 


Loligo opalescens 


51-54 


P 


Octopus dofleini 


500 


Martin et al., 1970 



4.2 /лп in length; it was divided externally into 3 regions clearly visible with phase- 
contrast microscopy (PI. 5). In a late spermatid, in which the nucleus is still swollen, 
having as yet not become completely condensed, the anterior acrosomal moiety and the 
posterior mitochondrial moiety could be readily distinguished (PI. 5, s). This mito- 
chondrial middle piece consists of 4-6 globular mitochondria (5-6 according to Personne 
& Anderson, 1970) surrounding the centriolar cone, from which the simple flagellum 
takes its origin. After such spermatozoa have been exposed to egg-water the acro- 
some can be seen to have discharged (Fig. 2), giving rise to a 1 ¿on acrosomal filament. 
These observations were confirmed using the slightly smaller gametes of Gibbula 
umbilicalis, and are in line with observations by Dan (1956) on other archaeogastropods 
{Scutus, Turbo, Tegula, Monodonta, Calcar, Lunella and Clypidina). In normal ferti- 
lization of marine invertebrates, this acrosomal reaction plays a key role in species- 
specific recognition, accomplished at the sub-cellular level in primitive molluscs. 

The spermatozoa of chitons, also externally fertilizing forms, are rather similar, 
in that the flagellum is again rather simple and placed in contact with the mitochon- 
dria at the centriolar cone. The length of the spermatozoon of Acanthochitona crinitus, 
for instance, is approximately 65 ßm, of which the head constitutes 10 pm (PI. 2H). 
Approximately l/2 of the head-length is taken up by the slender, tapering acrosome 
(described previously for Lepidochitona by Retzius (1906) and Rothschild & Tyler 
(1955)), which in the chitons does not alter appreciably during egg-water tests in the 
laboratory. The 4 globular mitochondria lie asymmetrically at the rear of the nucleus; 
these organelles are easily displaced. 

The spectacular acrosomal reaction of some bivalve mollusc sperm is now well 
documented, especially in Mytilus (Niijima & Dan, 1965; Galangau, 1969), and in 
Barnea (Pasteéis & Harven, 1962) in which the gametes are in many ways similar to 
those of the gastropod Gibbula, described above. In the North American bivalve 
Transennella tantilla, however, the proportions of the various parts of the head are 
strikingly different (Fig. 2). The head is 17-18 jum in length, occupying nearly l/4 
of the total length of the cell. But the nucleus itself is of normal size and shape, about 
2.4 /um in length, while the undischarged acrosome is fully 15 дт in length. The 
mitochondrial middle piece is extremely small, only 1 цт long. This gamete resem- 
bles morphologically that of a mesogastropod rather than that of Mytilus or Gibbula. 

These gametes described above are very simple in plan and are found, as Franzén 
(1955) has stressed, in externally fertilizing molluscs. The spermatozoa of cephalopods 



THOMPSON 181 

are of the same general kind except in Octopus dofleini martini, however, even though 
these advanced forms have evolved a system of courtship and copulation. In Loligo 
opalescens (Fig. 2), for example, the proportions of nucleus, mitochondrial middle 
piece and flagellum (Martin et al., 1970) are similar to those encountered in, for 
instance, Gibbula or Mytilus. There are important differences, however. It can be 
seen v from the diagram (Fig. 2) of Loligo opalescens that the mitochondrial moiety 
(forming a spur in many cephalopods, but not in Octopus dofleini (Martin et al., 1970)) 
and the centriolar cone are asymmetrical and, to a great extent, structurally inde- 
pendent of one another. Noacrosomecouldbe detected by optical microscopy, although 
known to be present in Octopus vulgaris (Galangau, 1969) and in O. dofleini (Martin 
et al., 1970). A diminution in the importance and size of the acrosome would be 
expected in animals such as cephalopods in which species-specific recognition occurs 
as the result of adult and spermatophoral physiological and behavioural factors, rather 
than at the level of the cell or of sub-cellular constituents, as occurs in non- copulating 
molluscs. 

In the cephalopods the evolution of spermatophoral packaging during copulation, and 
the concomitant lack of need for spermatozoan flagellation during the act of transfer, 
or for dynamic acrosomal participation in species-specific recognition, have led to 
the retention of a male gamete of an apparently rather primitive type. 

In higher molluscs of the Gastropoda, however, the evolutionary acquisition of 
systems of copulation, and, in the highest forms, of functional simultaneous herma- 
phroditism, has been accompanied by radical changes in the structure of the sperma- 
tozoa. From the examples shown us by the cephalopods, we might expect the loss of 
the acrosome and the retention of a simple flagellum and its fuel-system, the short 
mitochondrial mid-piece. Instead, we find the acrosome to be retained and even 
greatly enlarged, as in Theodoxus and its allies (Retzius, 1906; Hanson, Randall & 
Bayley, 1952; Galangau, 1969; Giusti, 1969; personal observations), while the mito- 
chondria and flagellum have increased tremendously in importance. The mitochondria 
may form prominent spiralling ridges, while their cristae become transformed in 
various ways (André, 1962), increasing the intimacy of their association with the axo- 
neme of the flagellum, and the axoneme itself may become transformed from the 
primitive 9 + 2 arrangement to the 9+ 9 + 2 system characteristic of the higher (inter- 
nally fertilizing) vertebrates (Bradfield, 1955) and of many insects (for instance, in 
the fire-ant Solenopsis (Thompson & Blum, 1967)). As Fawcett & PhiUips (1970) 
point out, there is currently a concensus of opinion that such outer "coarse" Y fibres 
represent additional motor elements which have evolved in connexion with spermato- 
zoan locomotion in a more viscous medium. The nucleus remains the least modified 
structure in these higher gastropods although it may become pierced throughout its 
length by the flagellum (Retzius, 1906; Walker & Macgregor, 1968; Galangau, 1969). 
Moreover, it will be seen that in Cipangopaludina (Yasuzumi & Tanaka, 1958), Aplysia, 
Umbraculum and many other euthyneurans, the nucleus itself becomes helically coiled, 
a phenomenon found elsewhere in the insect Dahlbominus (Wilkes & Lee, 1965), in 
some fish and birds (Stanley, 1971; McFarlane, 1963) and in the toad Xenopus laevis 
(personal observations). 

As the structures derived from the spermatid mitochondria became enlarged in the 
spermatozoa of higher gastropods, so too does the amount of food material enclosed 
within the gametes during late spermiogenesis. In some cases the predominant food 
reserve of ripe autosperms has been identified as glycogen (Personne & André, 1964; 
Anderson & Personne, 1970). What purpose such reserves possess during the normal 
functioning of the reproductive organs is far from clear. In internally fertilizing 
Mollusca it might be expected that exogenous sources of energy, like the fructose of 
mammalian seminal plasma, would be needed, but not endogenous mitochondrial 



182 PROC. FOURTH EUROP. MALAC. CONGR. 

glycogen. It is only in gametes of externally fertilizing animals that the metabolic 
substrates must all be endogenous. 

It is also strange that modifications, such as the 9 + 9 + 2 axoneme, the greatly 
elongated tail, and the posterior extension and intimate disposition of the mitochondrial 
derivatives, should be found in those very gastropods which, because they possess 
behavioural and mechanical devices designed to bring about internal fertilization, 
make the least demands on the locomotory powers of their male gametes. These and 
other observations lead to the recognition of a remarkable paradox, namely, that in 
those molluscs in which sperm motility might be considered important, the gametes 
have a small flagellum of the 9 + 2 type, tiny mitochondrial fuel-stores and the neces- 
sity to move considerable distances through a hostile external medium. On the other 
hand, in the majority of those molluscs in which the male gametes have need of their 
own means of propulsion solely during the moments during which they penetrate the 
protective investments of the egg, the spermatozoa are equipped with a greatly en- 
larged flagellum of the 9 + 9 + 2 type and relatively enormous mitochondrial and other 
fuel-stores. 

The remainder of this paper will be devoted to a description of some of the structural 
details of the spermatozoa of higher gastropods. At the present time they do not 
enable the resolution of the paradox outlined above. They may, however, contribute 
to the accumulation of the essential basic functional morphological information. What 
is next needed is more information about the behaviour of the spermatozoon while it 
is actually approaching and entering the egg, together with an analysis (in media of a 
controlled range of viscosities) of the pattern of utilization of the endogenous metabo- 
lic substrates present in the allosperms of the euthyneuran gastropods. 

EUTHYNEURAN SPERMATOZOA 
A. BULLOMORPHA 
Acteon tornatilis (Fig. 1; Pis. 3B, 4) 

Each spermatozoon from the vesicula seminalis measured approximately 230 /im in 
life, of which the head accounted for 4 ^m (including a 2 цт long acrosome). The 
head exhibited a helical twist of about 2 full turns (PI. 3B). After staining with acri- 
dine orange, live gametes gave a strong green emission detected with the fluorescence 
microscope, but the acrosome did not under any circumstances fluoresce. If sub- 
jected to hypertonic sea water or other serious osmotic stress, the nucleus readily 
exploded, showing the true shape of the acrosome (PI. 4A), and revealing that the 
centriolar region of the flagellum normally fits into a pit (1 /лп in depth) in the rear 
of the nucleus. 

The tail is divided into a mitochondrial mid-piece and a posterior mitochondria- 
free tail-piece (Fig. 1; PI. 4B). This division was not detectable by optical micros- 
copy and was therefore missed by Franzén (1955). Another important difference along 
the tail is that the mid-piece is ensheathed by 2 unit-membranes (PI. 4C, E) whereas 
the tail-piece has only 1 unit-membrane. The morphogenesis of this remarkable 
phenomenon would be of considerable interest. In the mid-piece, 4 mitochondrial 
derivatives run a spiral course (PI. 4A, ms) around the axoneme, which is itself 
ensheathed by a strong, closely adherent membrane, and consists of 9 doublets 
surrounding a central pair. Some evidence was obtained that coarse Y fibres were 
present outside the doublets, but only in the initial proximal region of the axoneme. 
The diameter of the axoneme was (in sectioned material) 0.25 ^m, approximately equal 
to the maximal girth of each of the 4 major mitochondrial derivatives. 

The 4 mitochondria are greatly elongated (Fig. 1, md; PI. 4G, ms). They originate 
in the neck of the gamete and spiral around the axoneme for varying distances (Fig. 1). 



THOMPSON 18 3 

In the neck, the 4 moieties can be distinguished but at a level approximately 60 /um down 
the tail only 2 moieties are present, and after a further 60 jum only 1 mitochondrial 
ridge spirals around the tail, having a crest to crest length of 2,6-2.8 цт (Fig. 1). 
So far as fine -structure is concerned, each mitochondrion has some similarity to a 
somatic organelle, possessing recognizable cristae (PI. 4C, E, mc), but, towards the 
rear, each mitochondrion becomes more solid, its lumen being restricted, so that 
cristae may no longer be found (PI. 4D). Flattened vesicular structures of unknown 
significance or homology lie between the mitochondria, (PI. 4C, E, lm), and may be 
observed in some longitudinal sections to join the outer membranes of adjacent 
mitochondria. 

Behind the mitochondrial mid-piece of the tail, and marked off from it by a line of 
disjunction (PI. 4B, zd), is the tail -piece, through the centre of which runs the axoneme 
to the tail tip (Fig. 1; PI. 4F, ax). The girth of the tail is similar in mid-piece 
and tail-piece regions. In the tail-piece, the axoneme lacks a distinct bounding 
membrane (PI. 4D, F), the cell wall consists of only 1 unit-membrane (PI. 4G, 
arrowed), and the space around the axoneme is packed with granules, probably of 
glycogen (Anderson & Personne, 1970). 

Bulla ampulla (Fig. 5; PI. 2G) 

The sperm-length overall was 106-115 дт, of which the nucleus took up 8 цт. On 
its anterior tip was the tiny conical acrosome, less than 1 /um in length. The banana- 
shaped nucleus smoothly continued the pitch and wavelength of the single mitochondrial 
spiral keel of the tail. The wavelength of this spiral was 9 цт (Fig. 5). The nucleus 
was ridged externally, the ridges spiralling around the head (shown diagrammatically 
in Fig. 5). In fact, ultrastructural observations on sections passing through the 
sperm-head reveal that 5-11 individual ridges may be present, as indicated in whole- 
mount preparations (PI. 2G, hg). 

Although only 1 major mitochondrial spiral could be detected on the tail, sections 
revealed a much smaller, second, subsidiary mitochondrial derivative travelling 
back from the neck for a short distance. This could not be shown in Fig. 5. The 
mitochondrial spiral peters out approximately half way back along the tail, leaving 
50 /im of the tail at the rear exhibiting no helical structures. At the extreme rear 
tip, a short length of more or less naked axoneme protrudes conspicuously (Fig. 5). 

Hydatina physis (Fig. 5; PI. 2E) and Haminea virescens (Fig. 3). 

These gametes, as can be seen from the illustrations, differ only slightly from the 
spermatozoon oí Bulla ampulla, described above. Asean be seen in Fig. 3, the sperma- 
tozoon of Haminea virescens is very different from Dupouy's (1960) description of 
H. navícula. Dupouy does not illustrate or mention any helical tail structures, and 
this omission, together with his claim that these gametes are polymorphic (as is 
known to occur in certain prosobranch gastropods) urgently requires re-investigation. 

B. PYRAMIDELLOMORPHA 

Odostomia sp. (Fig. 3; PI. 8D, E, F) 

The length varied greatly, extremes being 750-876 цт, of which the head occupied 
7.3 ¿an. The cylindrical acrosome was about 1.8 /im in length. The slightly curved 
nucleus led smoothly into the characteristic pitch and wavelength of the single mito- 
chondrial spiral keel. The wavelength was 9.0 дт; there were about 45 helices in 
all, leaving naked the rearmost l/2 - 1/3 of the tail. Shoulder-like structures sur- 
rounding the neck were prominent features (Fig. 3). Such structures in gastropod 
sperms are sometimes misleadingly called "ring centrioles." A more elusive fea- 
ture was a possible intra-nuclear filament, more obvious in some preparations than 



184 PROC. FOURTH EUROP. MALAC. CONGR. 

others. Fine -structure studies indicate that the appearance of a filament in this 
situation is in fact spurious. 

Sections through ovotesticular spermatozoa (PI. 8D, E, F) show that vestigial 
cristae are present in the single mitochondrial derivative (ms) and that numerous 
membranous vesicles (similar to those described above for Acteon) form a packing 
around the axoneme (PI. 8E, lm). No glycogen could be detected in any of the pre- 
parations. 

Odostomia columbianus (Fig. 3). 

The spermatozoa of this species were smaller, 250 цт in length, than those of the 
above, and showed other important differences. The wavelength of the single mito- 
chondrial spiral keel was 6 jum but the spiral consisted of only 3-4 full turns so that 
by far the greatest length of the tail lacked the mitochondrial sheath. Differences of 
a minor kind were also evident in both the head and neck (Fig. 3). 

These observations strongly support Franzen's (1955) contention that the pyramidel- 
lids possess spermatozoa clearly belonging to the euthyneuran type. 

С PLEUROBRANCHOMORPHA 

Umbraculum sinicum (Fig. 4; Pis. 6B, 8A) 

The overall length of these remarkable gametes was approximately 225 ¿mi, of which 
the helically disposed nucleus occupied 22 цт. PI. 8A illustrates that the nucleus (n) 
spirals around the axoneme (ax), shown diagrammatically in Fig. 4. A cylindrical 
acrosome, less than 1 цт in length, projected from the front of the spermatozoon. 
The flagellum travels from the rear of this acrosome to the posterior tip of the tail. 
The 7 helices of the nuclear spiral are continued smoothly rearwards down the tail 
by the single mitochondrial spiral keel. The wavelength of these spirals was 3.0- 
3.5 /um. The mitochondrial keel consisted of about 50 helices. The terminal 35 /mi of 
the tail lacked spiral features and was distinctly swollen (Fig. 4; PI. 6B, tp). Un- 
fortunately no sections pass through this tail-piece, in the limited amount of material 
presently available for study, but it is inferred that this swollen region of the tail is 
homologous with the glycogen-filled tail -piece of Acteon (Fig. 1, tp). 

Pleurobranchus peroni (Fig. 5; PI. 8C) 

The spermatozoa of Pleurobranchus are very different from those described above 
for Umbraculum. 

The length overall was 180-190 цт, of which the nucleus accounted for 7-7.5 шп. 
The acrosome was less than 1 /mi in length. The acrosome, nucleus, and tail form 
integrated parts of a smoothly helical configuration, the pitch and wavelength being 
rather uniform from 1 end of the cell to the other. The wavelength of these helices 
was approximately 4.5 цт. The number of helices exhibited by the nucleus was, 
surprisingly, variable in different specimens, sometimes 1 full turn, sometimes 2 
(Fig. 5). The total number of spirals visible along the length of the whole cell was 
45-46. 

Ultrastructural observations (PI. 8C) show the nucleus to be ridged (5 prominent 
ridges were visible in transverse sections through the sperm-head), very different 
from the cir cum -flagellar helical nucleus of Umbraculum (compare Figs. 4 and 5). 
The single prominent mitochondrial spiral keel contained granular material, probably 
glycogen (PI. 8C, g), and similar material could be found around the axoneme fibres 
near the neck. The centriolar region of the axoneme is located deep within a conical 
crypt in the rear of the nucleus. 



THOMPSON 185 



Berthella plumula 



Although rather larger than the spermatozoa of Pleur obranchus , gametes of B. 
plumula agree closely, and, like P. peroni, are very different from those of Umbra- 
culum . 

D. APLYSIOMORPHA 

This account is based chiefly upon published findings (Thompson & Bebbington, 1969, 
1970) dealing with Aplysia, but comparative observations have since been made on 
spermatozoa of other aplysiomorphs. As has been stressed (Thompson & Bebbington, 
1970) the spermatozoa of aplysiids have in the past been misinterpreted in various 
ways, and this is, perhaps, not surprising in view of their structural complexity. 

Aplysia spp. (Fig. 6; Pis. 7, 9B) 

Three North Atlantic species were investigated; these were Aplysia depilans, A. 
fasciata and A. punctata. Only minor differences were noted between these species. 
In overall length the gametes ranged from 155-228 pm. The nucleus is a cylinder, 
0.2-0.4 ¡j.m in diameter, which forms a helix (PI. 9B) of 5-7 turns. The nucleus extends 
to the anterior tip of the head; noacrosome could be detected. The flagellum originates 
just behind the anterior extremity of the head, and extends over nearly the whole 
length of the cell. In sections through the flagellum, the familiar 9 peripheral fibre- 
doublets could be recognised. Radial material extends from each fibre-doublet towards 
the central pair of fibrils, around which is a set of struts of unknown function. The 
diameter of the flagellum was approximately 0.22 цт. Two mitochondrial strands 
spiral around the flagellum; they are disparate in girth. Only the larger strand is 
clearly visible in live spermatozoa under phase-contrast microscopy; it forms a 
projecting spiral keel (Fig. 6; PL 7, pmd), while the other moiety is detectable only in 
sectioned material (Fig. 6; PL 7, smd). These may be termed the principal and sub- 
sidiary mitochondrial derivatives. The former contains quantities of granules (see 
Thompson & Bebbington, 1969, pi. 8A-E), believed to be glycogen. 

Dolabella auricularia (PL 8B), Dolabrifera dolabrifera, Bursatella leachi and 
Phyllaplysia taylori 

Optical and electron microscopic studies of these aplysiids showed their gametes 
to conform to the plan described above for Aplysia. One noteworthy feature is that 
in Dolabella (PL 8B) regular transverse rungs divide up the principal mitochondrial 
derivative; these rungs (which are less easy to detect in the other species) are pre- 
sumably derived during spermiogenesis from the mitochondrial cristae of the 
spermatid nebenkern. 

E. NUDIBRANCHIA 

This account is based chiefly upon published findings (Thompson, 1966) dealing 
with Archidoris, but more recent observations on this and other nudibranchs have 
been added. 

Archidoris pseudoargus (Fig. 7; Pis. 1, 9A, 10, IIA). 

The appearance of mature spermatozoa under various conditions of optical micro- 
scopy is shown in PL 1. The overall length is 208-210 цт, of which the banana-shaped 
head takes up 8-9 цт. PL 9 A shows the head in lateral view, with the short acrosome 
on the anterior tip. Samples of autosperms and allosperms were subjected to a 
variety of tests using preparations of egg-water (employing eggs from the ovotestis) 



186 PROC. FOURTH EUROP. MALAC. CONGR. 

and controls in sea water, but no acrosomal reaction could be induced. The bulk of 
the sperm-head was occupied by the nucleus, whose contents were coarsely striated, 
the long axes of most of the striae being coincident with that of the sperm (PI. 10). The 
nucleus was bounded by a nuclear membrane and the whole head ensheathed by the 
stout cell-membrane, continuous with that of the tail. The superficial spiral filament 
mentioned and illustrated in my 1966 paper is now thought to be spurious, although 
the whole head is in life curved in such a way as to hint at a helical pattern (Fig. 7). 
Details of the centriolar cone are described reasonably accurately in that paper and 
will not be repeated here. 

The tail is illustrated diagrammatically in Fig. 7 and a micrograph of a freeze- 
etched preparation is shown in PI. IIA. The cytoplasm of the tail is bounded by a 
fine spirally striated sheath. The axis of the tail consists of a central fibre-doublet 
with a ring of 9 peripheral doublets; the diameter of the axoneme in sections is 0.17 
мт. The axis is bilaterally symmetrical and the plane of symmetry remains unaltered 
along the length of the tail. The spirally keeled mitochondrial derivative (Fig. 7; 
PI. IIA) commences just behind the head and winds (in a clockwise direction when 
viewed from the front) to the tip of the tail. The wavelength of the spiral varies from 
5 to 11 цт after different methods of preparation for electron microscopy, but is 
constant along any individual sperm-tail. The crest to trough amplitude also shows 
individual variation; but superimposed upon this is a diminution in amplitude from 
neck to rear. The mitochondrial derivative possesses a lumen, 0.25 //m wide at its 
maximum, filled after fixation with a loosely coagulated material, not glycogen granules. 

Observations on activation, behaviour and storage of spermatozoa of Archidoris 
have been published elsewhere (Thompson, 1966). 

Tritonia festiva (Fig. 8; PI. 2F), Dendronotus iris (Fig. 8), Cadlina laevis (Fig. 8), 
Armina californica (Fig. 9) and Hermissenda crassicornis (=Я. opalescens) ( Fi S« 9 ) 

The illustrations show a close similarity in these nudibranchs, selected as examples 
from all the major subdivisions of the group, to the spermatozoa of Archidoris 
pseudoargus . Of course, sizes and proportions vary from species to species, but the 
basic plan remains, in the nudibranchs, the same. Only the shape of the acrosome 
shows significant variation. In the majority of the nudibranchs this structure forms 
a short, straight rod, as in Archidoris, but in some species, for instance, of Hermis- 
senda and of Dendronotus, the acrosome may be helically disposed. In Dendronotus 
iris (Fig. 8) a proportion of the gametes have a helical acrosome, while in the remain- 
der this organelle is straight; the significance of this remarkable dimorphism is not 
understood. In Hermissenda crassicornis is found another feature of uncertain im- 
portance; the mitochondrial helix terminates approximately 50 /im from the tail tip 
(Fig. 9). 

F. PULMONATA 

Planorbarius corneus (Fig. 10; Pis. 2B, 3C, 12, 13A), Physa gyrinus, P. fontinalis 
(PI. 11C), Lymnaea peregra and L. stagnai i s (Fig. 11; PI. IIB) 

In these basommatophoran species, already the subjects for productive research 
(Selman & Waddington, 1953; Anderson & Personne, 1970), the spermatozoa appear 
to show a high degree of uniformity. 

In Planorbarius corneus, for example, the length overall was 720 jum, of which the 
tiny head accounted for only 6.5 /um, including the 1.5 цт acrosome. The nucleus had 
a spiral twist (Fig. 10) as well as bearing superficial helical ridges and grooves (PI. 
2B, hg). The centriolar cone fits into a deep pit situated in the rear of the nucleus 
(Fig 10). The axoneme, with its basic pattern of 9 + 2 elements (9 + 9 + 2 just behind 
the head, as shown in PI. 12), is ensheathed by a thick layer of granular material 



THOMPSON 187 

(glycogen), through which spiral numerous organelles (PI. 13A, ms). None of these 
stands out to form a spiral keel of the type found in the Opisthobranchia, but the largest 
and most conspicuous are a pair of strong mitochondrial elements (Fig. 10; Pis. 12, 
13A). Numerous other elements, probably also mitochondrial derivatives, spiral with 
these and may be studied in freeze-etched preparations. 

In other species, only minor differences could be discovered. In Lymnaea stagnalis 
(Fig. 11; PI. IIB), for example, the nucleus was not markedly spiral in overall shape, 
and the superficial helical grooves were exceptionally shallow. Such differences are 
essentially quantitative rather than qualitative. Perhaps more important is the fact 
that in certain species {Lymnaea peregra, for example) a glycogen-filled tail-piece 
may be found, posterior to the region of spiralling mitochondrial derivatives. 

Achatina fúlica, Helix pomatia (Fig. 11; Pis. 6A, 13B, 14A, B), Onchidium damelii (PI. 
2C), Ariolimax columbianus (Fig. 11; PI. 2D) and Hedleyella falconeri (Fig. 10; PI. ЗА) 

In the Stylommatophora there is an astonishing amount of variability of sperm type, 
more than has been found in any other comparable group of molluscs. They range 
from gametes which resemble those of the aplysiids (as in Ariolimax), through some 
which superficially recall those of Basommatophora (as in Hedleyella), to the stream- 
lined nudibranch-like spermatozoa of the higher stylommatophorans (such as Helix). 
Bayne (1970) was certainly in error when he wrote that in general the spermatozoa of 
pulmonates are "practically identical." 

in Helix pomatia,the overall length of the spermatozoon was approximately 850 цт, of 
which the head took up 12 jum, including the tapering acrosome 2 ц.т in length. A 
single mitochondrial spiral travels back from the neck to the tail tip. These helices 
have a wavelength of approximately 20 jum. The axoneme (consisting proximally of 
9+9 + 2 elements, distally of only 9 + 2, according to Grasse et al., 1956) is surrounded 
by densely granular periaxial material (glycogen), in which are located a spiralling 
series of pits. Into these pits fit similarly disposed pegs projecting inwards from the 
outer case of the sperm-tail, as shown in PI. 14A, B. The shape and some details 
of the texture of the material constituting the helical principal micochondrial deriva- 
tive are displayed especially well by the freeze-etching method (PI. 14A, B). The 
elongated, banana-shaped head bears faint superficial spiral markings. The gametes 
of Onchidium damelii and Achatina fúlica were, except for details of size and pro- 
portion, rather similar to those of Helix. 

The spermatozoa of Hedleyella falconeri are the longest possessed by any mollusc, 
measuring 1140-1400 ¡xm, of which the head accounts for only 10 ¡лт, including an 
acrosomal projection 1.5 дт in length. The nucleus exhibited several helical super- 
ficial ridges and grooves (PI. ЗА, hg), clearly visible with light microscopy. These 
grooves, which were 0.6 цт apart, continued smoothly into the neck blending with the 
spiral ridges surrounding the tail (PI. ЗА, ms). The tail ridges, believed to be mito- 
chondrial derivatives by analogy with what is known of other euthyneuran gametes, are 
4 in number (Fig. 10 md 1-4) for approximately 230 дт, but thereafter 3 of these 
moieties peter out so that the remainder of the flagellum is surrounded by only 1 
spiralling ridge (Fig. 10). 

The gametes of the American N.W. Pacific forest slug Ariolimax columbianus 
provide a useful comparison and gave quite close agreement with the work of Bayne 
(1970) on the fine-structure of a European species of related slug. In A. columbianus 
the overall length was 265 цт, of which the helically disposed nucleus occupied 11 цт, 
including the 3 ¡xm anteriorly situated acrosome (Fig. 11). An anterior prolongation 
of the nucleus accompanies the acrosome and is shown in PI. 2D. Overlapping the 
middle and rear part of the nuclear helices are a pair of mitochondrial derivatives 
which continue rearwards down the tail, winding round the flagellum. The total 
number of spirals counted along the whole length of the gamete was 63-64. 



188 PROC. FOURTH EUROP. MALAC. CONGR. 

CONCLUSIONS 

In the Euthyneura, Acteon shows the basic type of spermatozoon from which the 
others may have been derived. In Acteon, each spermatozoon possesses 4 distinct 
mitochondrial derivatives which pursue a spiral course around the flagellum. These 
all exhibit rung-like lamellar cristae. A posterior non-helical tail-piece contains 
endogenous food-stores in the form of closely packed glycogen granules. 

In scattered examples from higher groups of Euthyneura {Umbraculum, Lymnaea) 
such a discrete tail-piece is retained, but in most other euthyneuran spermatozoa the 
tail-piece has been abolished and the glycogen is contained within 1 or more of the 
helically wound mitochondrial derivatives. The entire length of the tail or principal- 
piece in the higher Euthyneura corresponds to the middle piece of Acteon. 

Endogenous food-reserves are most conspicuous in the Pulmonata and in the lower 
opisthobranchs and least developed in the Nudibranchia. 

In Acteon the tail -piece is surrounded by a single unit-membrane, but in the mito- 
chondrial middle piece there are 2 such discrete membranes. The morphogenesis 
of this remarkable difference is obscure, as also is the situation in other gastropods. 

In Acteon the nucleus exhibits incipient helical coiling. In scattered examples 
among the higher Euthyneura (Aplysia, Umbraculum, Ariolimax) this is exaggerated 
and the nucleus in some of these forms has come to be wound around the centriolar 
cone. The tendency towards nuclear coiling, like that towards the possession of 
various helical configurations in the tail, is a characteristic of euthyneuran sperm in 
general. 

In the higher Opisthobranchia a trend is detectable towards a reduction in the num- 
ber of mitochondrial derivatives visible along the tail, so that in Aplysia there are 
only 2 (one of these is vestigial), while in the nudibranchs there is only 1 principal 
mitochondrial derivative. 

In the Pulmonata a trend is detectable towards an increase in the number of separ- 
ate mitochondrial helices, up to a maximum of 7. 

In some euthyneuran orders (for instance, the Basommatophora, Aplysiomorpha and 
the Nudibranchia) the spermatozoa show a relatively uniform morphology, whereas in 
others (for instance, the Pleurobranchomorpha or the Stylommatophora) there is a 
great deal of heterogeneity. 

Gross sperm- morphology is useful in the taxonomy of gastropods only in allocating 
dubious forms to either the Streptoneura or the Euthyneura, so that such criteria 
clearly confirm the euthyneuran affinities of the Pyramidellomorpha. It is not useful 
in attempts to decide, whether, for instance, the Onchidiidae or the Succineidae are 
opisthobranchs or pulmonates. 

The greatest areas of ignorance at present surround the function of the endogenous 
food-reserves of euthyneuran spermatozoa, the hydrodynamics in vivo of external 
form in these helically wound gametes, the behaviour of gastropod male gametes during 
egg-penetration and amphimixis and the function of the acrosome in internally ferti- 
lizing molluscs. 

ACKNOWLEDGEMENTS 

I am deeply grateful for help at various stages of this work to Mr Alan Britton, 
Mrs J. Milton and Mr G. H. Brown. My colleague Mr W. L. Maxwell has kindly read 
and commented helpfully on the paper during its preparation. This research has been 
supported by grants from the Royal Society, the Leverhulme Trust and the Science 
Research Council. 



THOMPSON 



189 




ÍM- 



PLATE 1. Optical microscopy oí Ar chidoris pseudoargus spermatozoa. 



A, Wild phase-contrast xlOO oil; sperm in sea water. 

B, Zeiss Nomarski x40; sperm in sea water. 

C, Zeiss Nomarski xl6; sperm drying in a bubble. 

D, Zeiss Nomarski x40; sperm drying in a bubble. 



190 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 2. Electron micrographs of head structures of chiton and gastropod spermatozoa, dried 
in the vapour of osmic acid or formaldehyde. The scale in each case represents a true 1 ¡xm. 

A, Gibbula cineraria; B, Planorbarius corneus; C, Onchidium damelii; D, Ariolimax Colum- 
bians; E, Hydatina physis; F, Tritonia festiva; G, Bulla ampulla; H, Acanthochitona crinitus 



THOMPSON 
HEDLEYELLA FALCQNER1 ACTEON TORNATILIS 

\ 



191 



A 



П 



ms 
% 



a 




с 



(Mum 



Hjj 



sind 



pmd 




J. 



ax 



pmd 



PLANORBARIUS CORNEU Sg 

PLATE 3. Spermatozoa of euthyneuran gastropods. 

A, phase-contrast optical micrograph, Hedleyella falconeri; B, phase-contrast optical micro- 
graph, Acteon tomatilis; C, electron micrograph of a freeze-etched replica, Planorbarius cor- 
neus. 



192 PROC. FOURTH EUROP. MALAC. CONGR. 



PLATE 4. Electron micrographs of spermatozoa from Acteon tomatilis taken from the wide 
hermaphrodite duct (=vesicula seminalis). The scale in each case represents a true 1 ¡лт. 

A, whole spermatozoan head, dried in osmic acid vapour; the nucleus has disintegrated, re- 
vealing the more durable acrosome and distal centriole. Four mitochondrial derivatives 
of equal size spiral around the flagellum. 

B, whole spermatozoon, region of disjuncture between the middle and tail-pieces. 

C, transverse section through the tail just behind the head, showing the 4 equal mitochondrial 
derivatives (numbered) with their distinct cristae. The cell membrane is double, i.e., 
consists of 2 unit membranes (solid arrows). By contrast, in an oblique L. S. of part of 
the tail-piece of another spermatozoon, the cell membrane may be seen to consist of only 
1 unit membrane (interrupted arrow). 

D, transverse sections through numerous sperm- tails, mostly through the mid-piece, (showing 
4, 3, 2 or 1 mitochondrial derivatives), 2 passing through the tail-piece and showing the 
periaxial layer of glycogen. 

E, longitudinal sections through part of a sperm-tail in the mid-piece, showing typical cristae 
and the flattened lamellae that run between the 4 mitochondrial derivatives. 

F, longitudinal sections through sperm-tails, the 2 on the left being through the mid-piece, the 
others through the tail-piece and showing the periaxial layer of glycogen. 

G, longitudinal sections through sperm-tails, showing the mitochondrial spirals, and the gly- 
cogen layer of a section through a tail-piece, with its single cell membrane (arrowed). 



THOMPSON 



193 




ms 





ACTEON TORNATILIS "f 



4 




"*Ä <gjf < fr -, 



4 

•*•-■ ал j| 

- H 

I 

Л> — "g . 



- il 







194 



PROC. FOURTH EUROP. MALAC. CONGR. 




4L* *fc ■ h 



GIBBULA CINERARIA 



PLATE 5. Optical micrograph (phase-contrast) of living spermatozoa and late spermatids of 
Gibbula cineraria. 



THOMPSON 

HELIX РОМАНА 



195 





PLATE 6. Optical micrographs (phase-contrast) of living euthyneuran spermatozoa. 
A, Helix pomatia; B, Umbraculum sinicum 



196 



PROC. FOURTH EUROP. MALAC. CONGR. 



APLYSIA DEPILANS 




PLATE 7. Aplysia depilans allosperms. Section through the receptaculum seminis of a mated 
specimen, showing many sperm-heads cut transversely. The head contains 2 mitochondrial 
derivatives (of disparate sizes) and the nucleus, spiralling around the axoneme. 



PLATE 8. Electron micrographs of sections through spermatozoa of Euthyneura. 
each case represents a true 1 /mi. 



The scale in 



A, longitudinal section through part of the head of a seminal vesicle autosperm of Umbraculum 
sinicum, showing the nucleus spiralling around the axoneme. B, sections through allosperms 
in the receptaculum seminis of a mated adult Dolabella auricularia, showing a single mitochon- 
drial derivative, with conspicuous transverse cristae spiralling around the axoneme. Several 
sperms are sectioned through the head and show the helical nucleus at various levels. C, sec- 
tion through the vesicula seminalis of Pleurobranchus peroni, passing longitudinally through a 
nucleus with its conspicuous post-nuclear embayment within which the centrioles are situated. 
D-F, various sections through the ovotestis of a mature Odostomia sp. from the Pacific N. W. 
of the United States of America showing various features of spermatid fine-structure. 



THOMPSON 



197 




198 



A 



1um 



5 



PROC. FOURTH EUROP. MALAC. CONGR. 

/л 



r* ^j#* 




PLATE 9. Spermatozoa of euthyneurans . 

A, whole head of autosperm of Archidoris pseudoargus, dried in osmic acid vapour. 

B, section through allosperms of Aplysia fasciata, showing the nucleus spiralling around the 
axoneme in the head region. 



THOMPSON 



199 



* fri^P^^ MARCHIDORIS PSEUDOARGUS" 




PLATE 10. Archidoris pseudoargus allosperms. Section through the receptaculum seminis of 
a mated specimen, showing masses of orientated spermatozoa with nuclear material condensed 
into coarse longitudinal threads and the post-nuclear recess containing the centrioles. The tail 
contains the axoneme with the helically wound single mitochondrial derivative (md). 



200 



PROC. FOURTH EUROP. MALAC. CONGR. 



1um 







ARCHIDORIS PSEUDOARGUS 




PLATE 11. Electron micrographs of freeze-etched replicas of seminal vesicle autosperms of 
euthyneuran gastropods , showing details of the helical configuration of the tail and the pustular 
texture of the periaxial packing material. 



A, Ar chidoris pseudoargus 

B, Lymnaea stagnalis 

C , Physa fontinalis 



THOMPSON 



201 



1jjm 



pmcl 









PLANORBARIUS CORNEUS 



PLATE 12. Electron micrograph of a freeze-etched replica of autosperms of Planorbarius 
corneus. The specimens show structures of the tail region, just behind the neck. 



202 



PROC. FOURTH EUROP. MALAC. CONGR. 




PLATE 13. Electron micrographs of freeze-etched replicas of seminal vesicle autosperms of 
euthyneuran gastropods, showing details of helical structures in the tail. 



A, Planorbarius corneus 

B, Helix pomatia 



THOMPSON 



203 




PLATE 14. Electron micrographs of freeze-etched replicas of autosperms of Helix pomatia. 



A, showing 2 spermatozoa exposed in the tail region; B, showing the interior surface of the 
periaxial material with its characteristic pustulose appearance. 



204 PROC. FOURTH EUROP. MALAC. CONGR. 

ABBREVIATIONS USED IN THE ILLUSTRATIONS 

a, acrosome; ax, axoneme; c, centriolar area; cf, coarse y fibres; cs, cell sheath; 
dc, distal centriole; f, flagellum; g, glycogen; h, head; hg, helical grooves; lm, 
lamellae; mc, mitochondrial cristae; md, mitochondrial derivative; ms, mitochon- 
drial spirals; n, nucleus; pa, periaxial material; pmd, principal mitochondrial 
derivative; s, spermatid; sm, mitochondria of spermatid; smd, subsidiary mitochon- 
drial derivative; sr, superficial ridges; tp, tail-piece; zd, zone of disjunction. 

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THOMPSON 205 

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Spermatozoa of the giant octopus of the North Pacific Octopus dofleini martini. 

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206 PROC. FOURTH EUROP. MALAC. CONGR. 

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ADDENDUM 

Since this paper was prepared, further information has been obtained relating to the 
fine structure of spermatozoa of Acteon tornatilis. These gametes had presented 
many puzzling features, especially concerning the nature and homologies of the various 
unit-membranes along the tail. It has now proved possible to obtain and study longi- 
tudinal sections through the crucial areas, namely, the neck(Pl. 15)1 and t ne zone of 
disjunction between the mitochondrial mid-piece and the tail-piece (PI. 16). Slight 
osmotic swelling during the fixation of these preparations has clarified the relation- 
ships between the various membranes. The micrographs (Pis. 15 and 16) show for 
the first time that the inner unit-membrane of the mid-piece sheath is continuous, 
both in the neck and at the posterior zone of disjunction, with the outermost unit- 
membrane of the mitochondrial axonemal sheath in the mid-piece. The functional 
significance of this morphological continuity is not clear, but it may have been dic- 
tated by morphogenetic aspects of spermiogenesis. It should be rewarding to study 
sperm-maturation in Acteon. Unfortunately, it is a marine mollusc of sporadic 
occurrence and living material is difficult to obtain. 

In the last 2 years, my colleague Mr. W. L. Maxwell has carried out a survey of 
spermiogenesis in cephalopod molluscs. His studies on Eledone cirrhosa demonstrate 
a spermatozoon differing from the primitive type in that the head (both nucleus and 
acrosome) are helically wound, the axoneme possesses a 9 + 9 + 2 arrangement of 
fibrils, and the mature gamete reaches a length of 550 ¿¿m. Glycogen deposits occur 
solely in the tails of the spermatozoa of the octopod Eledone. Maxwell's studies on 
decapods show a range of gamete length from 46 дга (Loligo forbesi) to 120 ^m 
(Eusepia officinalis). These decapod sperm differ from those of other molluscs in 
that the mitochondrial portion of the mid-piece is separated from the axoneme by a 
complex folding of the plasmalemma. There appear to be no glycogen deposits in 
mature spermatozoa of decapod cephalopods. 



1 For Plates 15 and 16, see p 443-444. 



MALACOLOGIA, 1973, 14: 207-213 

PROC. FOURTH EUROP. MA LAC. CONGR. 

ARTCHARAKTERISTISCHE FEINSTRUKTUREN BEI NUDIBRANCHIERN 1 

Luise Schmekel 

Max -Planck -Institut für Zellbiologie, Tübingen und 
Zoologische Anstalt der Universität Basel 

ABSTRACT 

The fine structure of different cells of the epidermis, cerebropleural ganglia, 
digestive gland and reproductive organs has been investigated in 12 species of 
nudibranchs from the Gulf of Naples. Some cells, like the gland cells of the 
mucous gland, possess a similar ultrastructure in all species studied. Other 
cells show species-specific differences. Such species-specific features are 
found mainly among the differentiations of the Plasmalemm, among telosomes 
and mature secretion products, e. g., the definitive, mature form of the prostate 
granules is species-specific. Developmental stages of secretion granules and 
lysosomes agree in most species. 

Vor mehr als 25 Jahren hat der Tübinger Zoologe Alfred Kühn (1946) elektronen- 
mikroskopisch die einzelligen Schmetterlingsschuppen von einem Spanner und einer 
Mehlmotte untersucht. Er fand erhebliche Strukturdifferenzen zwischen beiden Arten 
und meinte, es müsse lohnend sein, diese Unterschiede in den verschiedenen systema- 
tischen Gruppen zu verfolgen und daran die Schmetterlingssystematik zu prüfen. Das 
Thema dieses Vortrages reicht also bis in die Frühzeit der Elektronenmikroskopie 
zurück. Dennoch werden Sie, als Sie es hörten, zunächst einen Augenblick gestutzt 
haben. Bei Protozoen sind artcharakteristische Strukturen auf Zellniveau evident und 
uns allen vertraut. Aber bei Metazoen? Da fällt uns eine Reihe von aus der Licht- 
mikroskopie her vertrauten, oft von Art zu Art verschiedenen Differenzierungen ein, 
wie Blutzellen von Vertebraten oder Nesselkapseln von Hydroiden. Darüberhinaus 
aber sind wir alle geneigt, mit zunehmender mikroskopischer Auflösung und dem Über- 
gang vom Lichtmikroskop auf das Elektronenmikroskop eine zunehmende Struktur - 
Übereinstimmung anzunehmen und vom Huhn auf die Vertebraten, von Aplysia auf die 
Mollusken zu schliessen. Weithin geschieht das mit vollem Recht. Golgiapparat, 
Mitochondrien, Mikrotubuli scheinen von funktionellen Differenzen abgesehen überall 
gleich gebaut, Zilien nach dem gleichen 9 + 2 Schema angelegt, usf. Gibt es darüber 
hinaus etwas, worin sich die Muskelzelle der Art A von einer Muskelzelle der Art 
В unterscheidet? Ja etwas, worin sich übereinstimmend die Muskel- und Nervenzelle 
einer Art A von Muskel- und Nervenzellen der Art В unterscheiden? 

Das gibt es, soweit ich bei den mir vertrauten Mollusken und Seeigeln sehe. Und das 
in diesen beiden Gruppen beobachtete scheint zu einem guten Teil auch für die übrigen 
Metazoen zu gelten. Artcharakteristische Strukturen finden sich in beiden Stämmen 
bevorzugt unter den Differenzierungen der Zelloberfläche (1), unter den Sekreten (2) 
und unter den Lysosomen (Hetero- und Autotelosomen) (3). Die Bilder, die ich Ihnen 
zur Demonstration zeigen werde, stammen alle von Nudibranchiern aus dem Golf 
von Neapel und betreff en meist Gattungs- und keine Artunterschiede, weil die Geinheiten 



1 Mit Unterstützung durch die Deutsche Forschungsgemeinschaft und den Schweizerischen National- 
fond zur Förderung der Wissenschaften. 

(207) 



208 PROC. FOURTH EUROP. MALAC. CONGR. 

von Artunterschieden in 10 Minuten nicht aufzuzeigen sind (Material und Methodik vgl. 
Schmekel, 1971). 

l.Wir hörten zu Anfang von der Schmetterlingsschuppe. Bei den Nudibranchiern 
spielen derartige Differenzierungen der Zelloberfläche eine weit geringere Rolle als 
bei den Insekten und betreffen z. B. die Ausbildung des Mikrovillisaumes. Ob die 
Mikrovilli lang oder kurz sind, kann z. T. funktionsabhängig sein, ob sie verzweigt, 
unverzweigt sind oder ein Reusenwerk bilden, ist artcharakteristisch. Ein Beispiel 
soll hier genügen. In der Mitteldarmdrüse der Aeolidoidea kommen neben anderen 
Zellen regelmässig zwei Zelltypen vor: phagozytierende Zellen, welche bei allen von 
mir untersuchten Arten unspezifisch sind und eine durchaus 'nichtssagende' Ober- 
fläche besitzen -und ausserdem Zellen mit einem hoch differenzierten Mikrovillisaum. 
Diese letzteren Zellen scheinen u.a. Substanzen pinocytotisch aus dem Mitteldarm- 
drüsenlumen aufzunehmen. Die Ausbildung ihres Mikrovillisaumes variiert von Art 
zu Art. Coryphella pedata (Montagu, 1815) zeigt schlauchförmige, unverzweigte, 
relativ locker stehende Mikrovilli. Trinchesia granosa Schmekel, 1965 trägt über 
jeder Zelle ein dichtes Polster mehrfach verzweigter und untereinander anastomos- 
ierender Mikrovilli (Abb. s. Schmekel & Wechsler, 1968). 

2. Sekretgrana und Vakuolen können bei den Nudibranchiern vollkommen unspezifisch 
gestaltet sein. Zu diesen mit unseren heutigen Methoden morphologisch unspezifischen 
Sekreten gehört z. B. dasjenige der Becherzellen in der Epidermis, der Mucuszellen 
im Ovidukt (Schmekel, 1971), aber auch die Vakuolenkörper in den Vakuolenz eilen der 
A eolidier epidermis. Die Vakuolenkörper sehen bei allen Aeolidoidea gleich aus 
(Schmekel & Wechsler, 1966, Abb. 6 und 13), fehlen aber bei den Doridoidea. Wir 
haben hier also gruppentypische, nicht aber artcharakteristische Gebilde vor uns. 
Sekrete können andrerseits aber auch in hohem Masse spezifisch strukturiert sein, 
wie z. B. im vorderen Genitalsystem das Sekret der Prostata (Abb. 1-4). 

Als Prostata wird bei den Nudibranchiern der drüsige Abschnitt des männlichen 
Ausführweges bezeichnet. Die Prostata kann eine einfache Gangerweiterung sein 
oder eine abgesetzte Drüse. Ihr Epithel ist einschichtig. Merokrine Drüsenzellen 
und bewimperte Stützzellen wechseln einander ab. Das Sekret der Drüsenzellen besteht 
aus einer feinst flockulären, 'hellen' Komponente und einer osmiophilen, granulären 
Komponente. Beide Komponenten liegen bei manchen Arten in getrennten Zellen 
(Chromodoris), bei anderen in gesonderten Vakuolen in einer Zelle (Peltodoris, Abb. 1) 
oder aber zusammen in einer Vakuole (Coryphella, Abb. 4b). Flockuläres Material 
und osmiophile Grana werden, ohne ihre Struktur zu ändern, ins Prostatalumen ab- 
gegeben (Abb. 2a, 4b), wo sie unverändert bis zur nächsten Kopula erhalten bleiben. 
Sie dienen während der Kopulation dazu, die Autospermien zu einem festen Spermien- 
ballen zu verkleben. Bei allen Arten lassen sich die ersten, Überall gleich aussehen- 
den, osmiophilen Primär-Grana im Bereich des Golgi-Apparates beobachten (Abb. 2). 
Die weitere Reifung führt bei allen 12 bisher untersuchten Arten zu durchaus ver- 
schieden strukturierten Sekreten, die auf verschiedene Weise ausgeschleust werden. 
Bei Trinchesia coerulea (Montagu, 1804) (Abb. 2a) bleiben die osmiophilen Primärgrana 
als kleine Einzelgrana erhalten und werden meist einzeln ins Lumen abgegeben, indem 
die Vakuolenmembran des Granum mit dem apikalen Plasmalemm verschmilzt und 
beim Offnen zum Teil des Plasmalemms wird. Bei Trinchesia ocellata Schmekel, 
1965 (Abb. 3) wachsen die Primärgrana homogen zu Grana mit einem erheblich gröss- 
eren Durchmesser als bei Trinchesia coerulea heran. Bei Flabellina affinis (Gmelin, 
1791) (Abb. 4a) wird die Vakuole zuerst stärker erweitert als das Granum und später 
unregelmässig weiteres osmiophiles Material angelagert, bis zuletzt pro Vakuole ein 



SCHMEKEL 



209 







■■ 



isa 




HV 



ABB. 1. Peltodoris atromaculata, Prostata. Dunkle Sekretvakuolen DV mit osmiophilen Grana 
(Abb. la, Vergr. 17500 x) und helle Vakuolen HV mit feinst flockulärem Material (Abb. lb, 
Vergr. 21600 x) aus verschiedenen Regionen einer Zelle. 



210 



PROC. FOURTH EUROP. MALAC. CONGR. 




b£ 




■ 





/*■ . V 









я w/ 



< 




■ 



M * - i: 






ABB. 2. Trinchesia coerulea, Prostata. Kleine osmiophile Sekretgrana SG im Drüsenlumen L 
(Abb. 2a, Vergr. 9000 x) und im Bereich des Golgiapparates G (Abb. 2b, Vergr. 24000 x). DR 
Drüsenzelle, ST Stützzelle. 



SCHMEKEL 



211 



t 



* 




Ш 

4P 



V 






. 



< 



N ^ 

AOL 



DR 






ABB. 3. Trinchesia ocellata, Prostata. Grosse osmiophile Sekretgrana SG in den Drù'senzellen 
DR. N Kern und V Vakuole einer Stützzelle ST (Vergr. 24000 x). 

grosses, oft noch unregelmässig osmiophiles Granum vorhanden ist. Bei Coryphella 
pedata (Montagu, 1815) (Abb. 4b) werden nach und nach in der sich vergrössernden 
Vakuole immer mehr osmiophile Einzelgrana angesammelt und gleichzeitig flocku- 
läres, helles Material angereichert. Die Einzelgrana verschmelzen nicht miteinander, 
sondern die Vakuolen mit vielen Grana gelangen in den Zellapex, wo die Vakuolen- 
membran aufgelöst wird, so dass eine einzige grosse, apikale Ansammlung von osmio- 
philen Grana und flockulärem Material entsteht. Die Ausschüttung erfolgt durch 
einfache Öffnung des Plasmalemms. Damit genug der ausserordentlich vereinfacht 
vorgetragenen Beispiele. 

3. Wir kommen nun zum dritten Bereich, in dem Artunterschiede zu erwarten sind, 
den Lysosomen. Ich darf zunächst kurz die Nomenklatur erläutern, de Duve & 
Wattiaux (1966) folgend: 



212 



PROC. FOURTH EUROP. MALAC. CONGR. 



N 

■ 




ABB. 4. Flabellinidae, Prostata. Abb. 3a Flabellina affinis (Vergr. 3000 x), reife S , halbreife 
S' und junge S" Sekretvakuolen. G Golgizone, MI Mitochondrium, N Kern. Abb. 3b Coryphclla 
pedata (Vergr. 16800 x), apikale Ansammlung von osmiophilen Grana und feinstflockulärom 
Material in den Driisenzellen DR. ST Stützzellen, L Drüsenlumen. 



SCHMEKEL 



213 



Primäre Lysosomen sind im Bereich des Golgiapparates liegende kleine Vesikel, 
die saure Hydrolasen enthalten. Der Inhalt dieser Vesikel kann zur Verdauung von 
zellfremder oder zelleigener Substanz verwendet werden. Im ersten Fall entsteht aus 
dem primären Lysosom und der Phagozytosevakuole ein Heterolysosom, im zweiten 
Fall aus primärem Lysosom und zelleigenem Material ein Autolysosom. Heterolyso- 
som und Autolysosom werden zu einem häufig keine oder nur noch schwache saure 
Phosphataseaktivität zeigenden Telosom verdaut. Das Telosom kann ausgeschieden 
werden. Wird es in der Zelle behalten, wird es oft weiter kondensiert zu einem 
Postlysosom. Die Telo- und Postlysosomen zeigen nun, worauf für Helix z. B. schon 
Mercer 1963 hingewiesen hat, häufig in verschiedenen Geweben einer Art das gleiche 
Aussehen und unterscheiden sich von denen einer zweiten Art. Artcharakteris- 
tisch strukturierte Telosomen finden sich bei Nudibranchiern z. B. meist in 
grösserer Anzahl in den Riesennervenzellen der Cerebropleuralganglien, kommen in 
geringerer Zahl aber auch in den kleineren Nervenzellen und den Gliazellen vor 
(Schmekel & Wechsler, 1968). Autolysosomen lassen im Unterschied zu den Telosomen 
i. allg. keine spezifischen Merkmale erkennen. Wichtig ist hier also wieder, was wir 
schon für die osmiophilen Primärgrana des Prostatasekretes beobachtet haben: art- 
charakteristisch ist nicht das Genesestadium, sondern das Speicherstadium, bzw. das 
Stadium, in dem die Kondensierung unterbrochen wird. 

Lysosomen und Sekrete sind Teil des Vakuolenapparates der Zelle. Fassen wir 
zusammen, so sind feinstrukturelle Unterschiede also als Differenzierungen der 
Z elloberf äche zu erwarten oder bei Material, das vorübergehend oder dauernd im 
Vakuolenapparat der Zelle gespeichert wird. Organellen des Elementarstoffwechsels 
zeigen dagegen bei den Nudibranchiern i. allg. keine spezifischen Feinstrukturen. 

Ich danke der Stazione Zoológica di Napoli für die guten Arbeitsbedingungen in 
Neapel. 

LITERATUR 

DE DU VE, Ch. & WATTIAUX, R. 3 1966, Functions of lysosomes. Ann. Rev. Physiol., 

28: 435-492. 
KÜHN, A. & AN, M., 1946, Elektronenoptische Untersuchungen über den Bau von 

Schmetterlingsschuppen. Biol. Zentralbl., 65: 30-40. 
MERCER, E. H., 1962, The evolution of intracellular phospholipid membrane systems. 

In: R. J. С Harris, The Interpretation of Ultrastructure. Vol. 1: 369-384. 

Academic Press, New York, U.S.A. 
SCHMEKEL, L., 1971, Histologie und Feinstruktur der Genitalorgane von Nudibranch- 
iern (Gastropoda, Euthyneura). Z. Morph. Ökol. Tiere, 69: 115-183. 
SCHMEKEL, L. & WECHSLER, W., 1967, Elektronenmikroskopische Untersuchungen 

über Struktur und Entwicklung der Epidermis von Trinchesia granosa (Gastr. 

Opisthobranchia). Z. Zellforsch, mikrosk. Anat., 77: 95-114. 
SCHMEKEL, L., 1968, Feinstruktur der Mitteldarmdrüse (Leber) von Trinchesia 

granosa (Gastr. Opisthobranchia). Z. Zellforsch, mikrosk. Anat., 84: 238-268. 
SCHMEKEL, L., 1968, Elektronenmikroskopische Untersuchungen an Cerebro-Pleural- 

Ganglien von Nudibranchiern. I. Die Nervenzellen. Z. Zellforsch, mikrosk. Anat., 

89: 112-132. 



MALACOLOGIA, 1973, 14: 215-220 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE BIOLOGY OF THE ARCHITECTONICIDAE, 
GASTROPODS COMBINING PROSOBRANCH AND OPISTHOBRANCH TRAITS 

Robert Robertson 

Academy of Natural Sciences of Philadelphia, Pennsylvania, U.S.A. 

The Architectonicidae (or "Solariidae") are a small, specialized family of primarily 
tropical marine gastropods that are of particular phylogenetic interest and importance 
because they combine prosobranch traits such as streptoneury with various opistho- 
branch traits. This paper reviews what has been learned to date about architectonicid 
higher category relationships. Studies are still in progress on their biology, specific- 
ally their systematics, ecology, life history, anatomy, histology, functional morphology 
and cytology (the latter aspects are being done in collaboration with Dr. George M. 
Davis). Most of our work is based on the tropical western Atlantic species Heliacus 
cylindricus (Gmelin). 

The family is a cohesive, well-defined group and consists of 3 principal genera: 
Architectonica (or "Solarium"), Philippia and Heliacus (or "Torinia"). Their shells 
range in shape from high trochoidal and narrowly umbilicate (Gyriscus) through dis- 
coidal and widely umbilicate to forms with disjunct, planispiral whorls (Spirolaxis). 
The genera have been variously divided into 2 subfamilies or even families; such 
divisions greatly overemphasize opercular or radular differences (among which there 
admittedly is structural diversity). 

There is little published anatomical information on architectonicids. The best work 
is Bouvier's (1886); Risbec (1955) and Merrill (unpubl.) have also studied their 
anatomy. 

Thiele (1929) grouped the family among the mesogastropods in the Cerithiacea 
primarily on the basis of Bouvier's work. Taylor & Sohl (1962) named a superfamily 
Architectonicacea, placed this in the Mesogastropoda, but noted that it and the Mathildi- 
dae "may prove to be primitive shelled Euthyneura." As long ago as 1928, Kuroda 
transferred the Architectonicidae to the opisthobranchs, but without stated reasons. 
More recently, Habe & Kosuge (1966) and Kosuge (1966) have grouped the Architecto- 
nicidae, Mathildidae, Epitoniidae, Janthinidae and Triphoridae in a new order or sub- 
order, the Heterogastropoda, which they placed between the Neogastropoda and Basom- 
matophora; they dispensed with subclasses and placed the Entomotaeniata (Pyramidel- 
lidae) and Cephalaspidea after the Basommatophora. This classification is unsatis- 
factory because the relationships between Triphoridae and the other 4 families seem 
highly tenuous and because the other families are separated from their nearest 
relatives (mesogastropods, pyramidellids and cephalaspids). 

As has long been known, the Architectonicidae have hyperstrophically coiled larval 
shells (Robertson, 1963b). If the Pyramidellidae are to be considered opisthobranchs 
(Fretter & Graham, 1949, 1962), the Architectonicidae, Mathildidae and Cyclo- 
stremellidae (Moore, 1966) remain the only living families with this character that 
are still classified with the prosobranchs. It was this character plus the pigmented 
mantle organs of larval pyramidellids that initially led Thorson (1946) to suggest 
that these are tectibranchs. Thorson later (1957) observed that larval Epitoniidae 
(or "Scalidae") have similarly pigmented mantle organs, and even though epitoniids 
lack hyperstrophically coiled larval shells, he hinted that these too might be tecti- 
branchs. Earlier, Knight et al. (1954) had already placed the "Scalacea" with the 
opisthobranchs, but without stated reasons. 

(215) 



216 PROC. FOURTH EUROP. MALAC. CONGR. 

All the known similarities between architectonicids and epitoniids are listed in 
Table 1. The information is partly from the literature and partly from unpublished 
data as noted. Similarities 4, 5 and 6 may be correlated with feeding habits, and simi- 
larities 8 and 9 are acknowledged to be inexact. Nevertheless, this many similarities 
seem to indicate that the 2 families are related. The relationships between architec- 
tonicids and pyramidellids seem closer, there being at least 7 uncorrected and exact 
similarities (Table 2). Risbec (1955) was also impressed by similarities between 
these 2 families. 

All the known prosobranch and opisthobranch traits of architectonicids are listed 
in Tables 3 and 4. Again, the information is partly from the literature and partly 
from unpublished data as noted. A fact to be stressed is that there are exceptions to 
nearly all the criteria by which opisthobranchs are distinguished from prosobranchs, 
and thus that there is no clearcut separation or objective way of defining the 2 sub- 
classes. Architectonicids combine a nearly equal number of traits of each subclass. 
They also combine at least 1 trait unknown among prosobranchs (Table 4, trait 7) with 
1 trait unknown among opisthobranchs (Table 3, trait 5). Architectonicids also have 
distinctive and highly specialized traits (Table 5), which make it unlikely that they 
gave rise to any other group. On the basis of shell matrix proteins, Ghiselin et al. 
(1967) believed Ar chite ctonica to be "an excellent precursor for the opisthobranchs 
and pulmonates. " The other living families that show a complex web of interrelation- 
ships between prosobranchs and opisthobranchs (combining various proportions of 
traits of both) include: Pyramidellidae, Mathildidae, Cyclostremellidae, Epitoniidae, 
Janthinidae, Rissoellidae, Omalogyridae and Acteonidae. More comparative informa- 
tion is particularly needed on the Mathildidae and Cyclostremellidae. 

Excluding these transitional groups, it must be acknowledged that prosobranchs 
and opisthobranchs show divergent evolutionary trends. Opisthobranchs probably 
diverged polyphyletically from lower mesogastropods, and the transitional groups 
help to show the sequence of evolutionary changes that occurred during the divergence^ 

Gastropods have commonly been divided into prosobranchs, opisthobranchs and 
pulmonates, but Boettger (1955) has advocated combining the latter 2 as the subclass 
Euthyneura. There would be as much reason to combine prosobranchs (Streptoneura) 
and opisthobranchs. I prefer to retain the 3 subclasses, but with the reservation that 
they can only be separated arbitrarily. 

TABLE 1. Similarities between Architectonicidae and Epitoniidae: 

1. Eyes near surface in swellings at outer bases of the tentacles. 

2. Streptoneury [note 1].* 

3. Long acrembolic proboscises. 

4. Postlarval feeding associations with coelenterates [note 2]. 

5. Esophagus cuticularized [note 3]. 

6. Some architectonicids with ptenoglossate-like radulae [note 4]. 

7. Pigmented mantle organs [note 5]. 

8. Hermaphroditism (but epitoniids protandric?). 

9. Chalazae (but in epitoniids these connect capsules containing 
numerous eggs, and the capsules are not in gelatinous masses). 



*See Notes on p 218, 219. 



ROBERTSON 217 

TABLE 2. Similarities between Architectonicidae and Pyramidellidae: 



1. Long acrembolic proboscises. 

2. Pigmented mantle organs [note 5]. 

3. Juxtaposed (dorsal and ventral) longitudinal ciliated tracts in mantle cavities [note 6]. 

4. Simultaneous hermaphroditism [note 7]. 

5. Spermatophores (some species in both groups) [note 8]. 

6. Chalazae connect capsules containing single eggs within gelatinous egg masses [note 9]. 

7. Hyperstrophically coiled larval shells [note 10]. 



TABLE 3. Prosobranch traits of Architectonicidae and exceptional opisthobranchs (Pyramidel- 
lidae included) with same traits: 

1. Entrance to mantle cavities directed anteriad, gills anterior to hearts and auricles anterior 
to ventricles (Acteon, Ringicula, Cylichna and Pyramidellidae, the latter usually without 
gills [note 11]). 

2. Spires of shells not reduced and bodies retractile into shells (various Cephalaspidea, all 
Pyramidellidae and some Thecosomata). 

3. Opercula present in adults (Acteon, Pyramidellidae, Retusa, Spiratellidae and Peraclididae). 

4. Streptoneury [note 1] (Acteon, Ringicula and Toledonia). 

5. Eyes near surface in swellings at outer bases of tentacles (no known opisthobranchs). 

6. Osphradia present [note 1] (Acteon, Diaphanidae and Pyramidellidae). 

7. Long acrembolic proboscises (Pyramidellidae). 

8. Salivary glands non-tubular [note 12] (some nudibranchs, etc). 

9. Velum with 4 long lobes [note 17] (any opisthobranchs?). 



TABLE 4. Opisthobranch traits of Architectonicidae, with exceptional prosobranchs (Epitoniidae 
included) with same traits: 

1. Feet very wide and with median anterior cleft (various prosobranchs). 

2. Tentacles slightly flattened, and ventrally ciliated and channeled (any prosobranchs?) [note 13]. 

3. Gills foliobranch [note 1], and main palliai water currents created by pair of longitudinal 
ciliated tracts (latter in Omalogyra). 

4. Pigmented mantle organs [note 5] (Omalogyra, Epitoniidae, etc.). 

5. No esophageal glands (Omalogyra, Epitoniidae, etc.). 

6. Simultaneous hermaphroditism [note 7] (Acmaea rubella, Cocculina, Omalogyra, Rissoella, 
Valvata and Lamellariidae [note 14]). 

7. Chalazae connect capsules within gelatinous egg masses [note 9] (no known prosobranchs). 

8. Hyperstrophically coiled larval shells [note 10] (Cyclostremellidae and Mathildidae, but these 
could be opisthobranchs). 



218 PROC. FOURTH EUROP. MALAC. CONGR. 

TABLE 5. Some of the apparently unique characteristics or specializations of the Architectonici- 
dae (some may occur only in Heliacus): 

1 . Ciliated omniphoric groove extends onto right side proximal outer surface of proboscis [note 1 5] . 

2. Ciliated dorsal crest divides exceptionally deep mantle cavity longitudinally (a superficially 
similar crest exists in viviparids), and all organs except the osphradium are adjacent to or 
open into the right chamber [note 1]. 

3. Uppermost duct in dorsal crest extends through nerve ring to a pore at middle of sole, from 
which a tough, elastic mucus thread is continuously extruded [note 15]. 

4. No penis; instead, long, coiled, tubular spermatophores [note 8]. 

5. Opercula paucispiral to multispiral, lamellate and conical, with peg projecting into foot (those 
of some Cyclophoridae are superficially similar). 

6. False spire of hyperstrophically coiled protoconch projects into teleoconch umbilicus , and 
protoconch and teleoconch axes slightly different [note 10] (also in Cyclostremellidae). 

7. Intraspecific larval shell size bimodality [note 16]. 

8. Arrested growth in an early postlarval stage (recorded as a distinct growth line on older 
shells) [note 17]. 

NOTES 

1. Architectonica: Bouvier, 1886; Heliacus: Robertson & Davis, unpubl. 

2. Heliacus spp. with zoanthiniarians (Robertson, 1967a; Marche- Marchad, 1969), Philippia 
(Psilaxis) with scleractinians (Robertson etal., 1970), and Philippia (Philippia) with actini- 
arians (Robertson & W. F. Ponder, unpubl.). The food of Architectonica remains unknown. 
My (1963a) hypothesis that all Epitoniidae feed on coelenterates has been strengthened by 
subsequently published information (Fager, 1968; Morton & Miller, 1968; Robertson, 1970a; 
Albergoni et al. , 1970). 

3. Robertson, 1970b. 

4. Architectonicid radulae range in structure from modified taenioglossate (5 teeth per trans- 
verse row in Heliacus) to ptenoglossate-like (with numerous teeth per transverse row in 
Architectonica) [Troschel, 1861, 1875; Thiele, 1928; Robertson, 1970b; Merrill, unpubl.]. 
The latter could be convergent with epitoniid radulae: a consequence of identical food. 

5. I intentionally use this vague terminology for the structure or structures that have been called 
a larval excretory organ (kidney) in larval opisthobranchs and a hypobranchial gland in adult 
epitoniids. Both in architectonicids and in pyramidellids I have observed these organs to be 
retained from the larva through metamorphosis and throughout life, and the same probably 
occurs in epitoniids. These usually darkly pigmented organs, so conspicuous in the larvae, 
become associated with the hypobranchial gland or gill in the adults. The pigment they release 
maybe repugnatorial. Further work is needed on the structure and function of these organs at 
different lifehistory stages and indifferent groups to determine whether they are homologous. 

6. Heliacus and Odostomia, s.l. : Robertson, unpubl. 

7. Both specimens of a pair of Heliacus cylindricus at Bermuda were found to have ripe sper- 
matozoa in the gonad; earlier, they had been transferring spermatophores and one of them 
had laid an egg mass (Robertson, unpubl.). Anatomical confirmation of simultaneous herma- 
phroditism in this and other architectonicids is still needed. 

8. Heliacus cylindricus and H. perrieri (Rochebrune): Robertson, unpubl. Pyramidellidae: 
Hóisaeter, 1965; Robertson, 1967b and unpubl. 



ROBERTSON 219 

ACKNOWLEDGEMENTS 

I thank Drs. George M. Davis, Vera Fretter, Alastair Graham and Henning Lemche 
for helpful discussions. These persons do not necessarily agree with all the views 
stated here. Part of the work was supported by National Science Foundation Grant 
GB-7008. 

LITERATURE CITED 

ALBERGONI, A., FRANCHINI, D. A., FRANCHINI, S. & SARTORE, G., 1970, Note 

sul Ritrovamento e sull'Habitat di Numerosi Esemplari di Opalia (Dentiscala) 

crenata (Linneo), e di altre Scalidae nel Mare di Almeria (Spagna). Conchiglie, 

6: 119-127. 
BOETTGER, C. R., 1955, Die Systematik der euthyneuren Schnecken. Verh. dtsch. 

zool. Ges. "1954." Zool. Anz., Suppl., 18: 253-280. 
BOUVIER, E.-L., 1886, Contributions à l'Etude des Prosobranches Pténoglosses. 

Bull. Soc. malacol. Fr., 3: 77-130. 
FAGER, E. W., 1968, A Sand-bottom epifaunal community of invertebrates in shallow 

water. Limnol. Oceanogr., 13: 448-464. 
FRETTER, V. & GRAHAM, A., 1949, The structure and mode of life of the Pyramidel- 

lidae, parasitic opisthobranchs. J. mar. biol. Assoc. U.K., 28: 493-532. 
FRETTER, V. & GRAHAM, A., 1962, British prosobranch molluscs; their functional 

anatomy and ecology. Ray Soc, London, xvi + 755 p. 
GHISELIN, M. T., DEGENS, E. T., SPENCER, D. W. & PARKER, R. H., 1967, A 

phylogenetic survey of molluscan shell matrix proteins. Breviora (Mus. Comp. 

Zool., Harvard), No. 262, 35 p. 
HABE, T. & KOSUGE, S., 1966, Shells of the world in colour. Vol. II. The tropical 

Pacific. Hoikusha, Osaka, Japan, vii + 193 p. 
HÖISAETER, T., 1965, Spermatophores in Chrysallida obtusa (Brown) (Opisthobranchia, 

Pyramidellidae). Sarsia, 18: 63-68. 



notes cont. 

9. Philippia (Psilaxis): Robertson, 1970b; Heliacus cylindricus and H. perrieri: Robertson, 
unpubl. 

10. Robertson, 1963b, 1964. In architectonicids, hyperstrophic coiling is abnormally retained 
throughout life: Robertson & Merrill, 1963. 

11. Risbec (1955) found a reduced gill in 1 pyramidellid. 

12. Architectonica: Bouvier, 1886; Risbec, 1955. 

13. Heliacus: Robertson, unpubl. ; the tentacles of Architectonica apparently are channeled 
medially (Bouvier, 1886). 

14. Confirmation is needed that the hermaphroditism in some of these prosobranchs truly is 
simultaneous and not protandric. 

15. Heliacus cylindricus: Robertson & Davis, unpubl. 

16. Architectonica nobilis Röding and eastern Pacific Heliacus architae (O. Costa): Robertson, 
unpubl.; Philippia (Psilaxis) radiata (Röding): Robertson, 1970b; P. (P.) krebsii Mörch: 
Robertson, 1964 and unpubl. There seems to be some genetic basis for the dimorphism. 

17. Robertson etal., 1970. 



220 PROC. FOURTH EUROP. MA LAC. CONGR. 

KNIGHT, J. В., BATTEN, R. L. & YOCHELSON, E. L., 1954, Status of invertebrate 
paleontology, 1953. V. Mollusca: Gastropoda. Bull. Mus. comp. Zool. Harvard 
Coll., 112: 173-179. 

KOSUGE, S., 1966, The family Triphoridae and its systematic position. Malacologia, 
4: 297-324. 

л л 

KURODA, T., 1928, Catalogue of the shell-bearing Mollusca of Amami-Oshima (Oshima, 

Osumi). Spec. Publ. Kagoshima-ken Ed. Invest. Comm., 126 p. 
MARCHE -MARCHAD, I., 1969, Les Architectonicidae [Gastropodes Prosobranches] 

de la Côte Occidentale d'Afrique. Bull. Inst. Fond. Afr. Noire, ser. A, 31: 461- 

486. 
MERRILL, A. S., unpublished [1970] The family Architectonicidae (Gastropoda: 

Mollusca) in the western and eastern Atlantic. Ph.D. Dissert., University of 

Delaware, xi + 338 p. 
MOORE, D. R., 1966, The Cyclostremellidae, a new family of prosobranch mollusks. 

Bull. mar. Sei., 16: 480-484. 
MORTON, J. & MILLER, M., 1968, The New Zealand sea shore. Collins, London and 

Auckland. 638 p. 
RISBEC, J., 1955, Considérations sur l'Anatomie comparée et la Classification des 

Gastéropodes Prosobranches. J. Conchyliol., 95: 45-82. 
ROBERTSON, R., 1963a, Wentletraps (Epitoniidae) feeding on sea anemones and 

corals. Proc. malacol. Soc. Lond., 35: 51-63. 
ROBERTSON, R., 1963b, The Hyperstrophic larval shells of the Architectonicidae. 

Amer, malacol. Union, ann. Reps., 1963, p 11-12. 
ROBERTSON, R., 1964, Dispersal and wastage of larval Philippia krebsii (Gastropoda: 

Architectonicidae) in the North Atlantic. Proc. Acad, natur. Sei. Philad., 116: 1-27. 
ROBERTSON, R., 1967a, Heliacus (Gastropoda: Architectonicidae) symbiotic with 

Zoanthiniaria (Coelenterata). Science, 156: 246-248. 
ROBERTSON, R., 1967b, The life history of Odostomia bisuturalis, and Odostomia 

spermatophores. Year Book Amer. Phil. Soc, 1966, p 368-370. 
ROBERTSON, R., 1970a, Review of the predators and parasites of stony corals, with 

special reference to symbiotic prosobranch gastropods. Pacif. Sei., 24: 43-54. 
ROBERTSON, R., 1970b, Systematics of Indo-Pacific Philippia (Psilaxis), architec- 

tonicid gastropods with eggs and young in the umbilicus. Pacif. Sei., 24: 66-83. 
ROBERTSON, R. & MERRILL, A. S., 1963, Abnormal dextral hyperstrophy of post- 
larval Heliacus (Gastropoda: Architectonicidae). Veliger, 6: 76-79. 
ROBERTSON, R., SCHELTEMA, R. S. & ADAMS, F. W., 1970, The feeding, larval 

dispersal and metamorphosis of Philippia (Gastropoda: Architectonicidae). Pacif. 

Sei., 24: 55-65. 
TAYLOR, D. W. & SOHL, N. F., 1962, An outline of gastropod classification. Mala- 
cologia, 1: 7-32. 
THIELE, J., 1928, Über ptenoglosse Schnecken. Z. wiss. Zool., 132: 73-94. 
THIELE, J., 1929, Handbuch der systematischen Weichtierkunde. Fischer, Jena, 1: 

1-376. 
THORSON, G., 1946, Reproduction and larval development of Danish marine bottom 

invertebrates, with special reference to the planktonic larvae in the sound 

(0resund). Medd. Danm. Fisk.-og Havunders., ser. Plankton, 4: 1-523. 
THORSON, G., 1957, Parasitism in the marine gastropod-family Scalidae. Vidensk. 

Medd. dansk naturhist. Foren., 119: 55-58. 
TROSCHEL, F. H., 1861, Ueber die systematische Stellung der Gattung Solarium. 

Arch. Naturgesch., 27: 91-99. 
TROSCHEL, F. H., 1875, Das Gebiss der Schnecken. Nicolaische Verlags -Buchhandlung, 

Berlin, 2: 155-158. 



MALACOLOGIA, 1973, 14: 221-222 

PROC. FOURTH EUROP. MALAC. CONGR. 

A COMPARATIVE STUDY OF SOME POLISH AND AMERICAN LYMNAEIDAE: 
AN ASSESSMENT OF PHYLOGENETIC CHARACTERS 

J. B. Burch 

Museum of Zoology, The University of Michigan 
Ann Arbor, Michigan 48104, U.S.A. 



ABSTRACT 



Electrophoretic and immunological studies show that the Polish Stagnicola corvus and the North 
American Stagnicola palustris elodes are very closely related in regard to their foot muscle proteins. 
These and their nearly identical shells are regarded to be indicative of their common ancestry; their 
similar shells are not the result of parallel evolution. Likewise, Polish Lymnaea stagnalis and the 
North American subspecies L. stagnalis jugularis (=appressus) are very closely related, but nei- 
ther shows close affinities to either of the Stagnicola species. Stagnicola corvus has in common 
with L. stagnalis a multifolded prostate gland, and like L. stagnalis, it lacks appendices at the proximal 
ends of both the uterus and the prostate gland. However, these anatomical peculiarities do not seem to 
relate S. corvus more closely to L. stagnalis than to other Stagnicola species. These anatomical charac- 
ters, rather than the shell characters, must be the result of parallel evolution. Or more probably (by 
inference from characters of other lymnaeids), a stagnicoline ancestor with tricuspid lateral teeth, a 
unifolded prostate gland, and lacking a penial swelling, as well as lacking proximal appendices on the 
uterus and prostate gland, gave rise to 2 stocks of stagnicoline snails. In one stock, the endocones and 
mesocones of the lateral radular teeth merged (or the endocones were reduced to obsolescence), the penis 
developed a stronger holdfast "knot," and appendices developed in the proximal parts of the uterus and 
prostate glands. Nevertheless, these modifications were only minor evolutionary changes, and a corres- 
ponding evolution of basic structural foot muscle proteins did not take place. Descendants of this stock 
occur in Eurasia, and they are apparently the only Stagnicola group found in North America. The other 
stock did not migrate from Eurasia, and retained the tricuspid condition of the first lateral radular teeth, 
and did not develop uterine and prostatic appendices or a well-developed penial "knot." However, the 
prostate gland became more highly folded. From this second stock Lymnaea s. str. may have evolved, 
retaining certain anatomical characters in the ancestral condition, but diverging significantly in shell 
shape, some anatomical characters, and especially in proteins (as evidenced by foot muscle). 

The patterns of characters and their evolution in the apparently ancient and now widely distributed 
family Lymnaeidae are very complex, and assessment of the importance of morphological characters, 
in every case, should be aided by auxiliary studies using immunological, electrophoretic, or other modern 
taxonomic methods. 



Published in extenso in: Zool. zh., 1971, 50(8): 1158-1168, coauthored with G.K. Lindsay and P.T. LoVerde. 




FIG. 1. Shells of American and Polish lymnaeid species used in this study. (1) Stagnicola palustris elodes 
(x2) [U.S.A.]; (2) Lymnaea stagnalis jugularis (xl) [U.S.A.]; (3) S. corvus (x2) [Poland]; (4) L. stagnalis 
(xl.2) [Poland]. 

(221) 



222 



PROC. FOURTH EUROP. MALAC. CONGR. 





FIG. 2. Precipitin reactions of North American 
and Polish lymnaeid snails. Arrows point to "non- 
identity" reactions. E =Stagnicola palustris elodes 
antigen, Ea = S. p. elodes antiserum, С = S. corvus 
antigen, S = Lymnaea stagnalis antigen, J = L. stag- 
nalis jugularis antigen, Ja = L. s. jugularis antise- 
rum. (1) S. corvus antigenx S. p. elodes antiserum. 

(2) S. corvus antigen x L. s. jugularis antiserum. 

(3) L. stagnalis antigen x S. p. elodes antiserum. 




(1) 



(2) 



(3) 



(4) 



(5) 



(6) 



CO 



FIG. 3. Acrylamide gel columns (the bottom "sepa- 
rating" gel only) showing esterase separations from 
snail foot muscle proteins. (1) Stagnicola palustris 
elodes, U.S.A. (2) Separation of a mixture of foot 
muscle extracts of S. p. elodes and S. corvus, Po- 
land. (3) S. corvus. (4) Separation of a mixture of 
foot muscle extracts of S. corvus and Lymnaea stag- 
nalis jugularis, U.S.A. (5) L.s. jugularis. ^Sep- 
aration of a mixture of foot muscle extracts of L.s. 
jugularis and L. stagnalis, Poland. (7)1,. stagnalis. 



MALACOLOGIA, 1973, 14: 222 



PROC. FOURTH EUROP. MALAC. CONGR. 
PROBLEMS OF GENERIC PLACEMENT IN AUSTRALIAN LAND MOLLUSCS 

Brian J. Smith 

National Museum of Victoria, Melbourne, Victoria, Australia 

ABSTRACT 



Because of its large land area, its wide range of habitats from tropical rainforests to large desert areas 
and because of its relatively complete geographical isolation, Australia has an extensive, varied and largely 
endemic land mollusc fauna. However, even though a fairly large amount of work has been carried out on 
this fauna, there is still a large measure of confusion of its taxonomic state, particularly at the generic 
level. This is caused by 2 factors. Firstly, Iredale erected a large number of genera with little or no 
proper generic description and with no attempt at revision of the groups. Secondly, the type specimens of 
many of the type species of the Iredalean genera and of the genera from which they were separated are held 
in overseas institutions, principally in Europe and Britain. It is intended to attempt to clarify the positions 
of all Iredalean genera in a series of revisionary papers, firstly for the land molluscs and hopefully even- 
tually for all the Iredale genera in doubt. 



MALACOLOGIA, 1973, 14: 223-232 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE USE OF ECOLOGICAL DATA IN THE ELUCIDATION OF SOME SHALLOW 
WATER EUROPEAN CARDIUM SPECIES 

P. J. C. Russell 1 and G. H0pner Petersen 2 

INTRODUCTION 

Throughout the last 2 centuries there has been much controversy concerning the 
validity of various Cardium species, in particular С glaucum Bruguière, due to both 
the lack of ecological data and the widely accepted use of the morphological characters 
of shell material alone as a basis for their classification (Russell, 1969). The re- 
sulting confusion was highlighted recently by the description of a new species from 
Danish waters (Cardium hauniense), which had been identified as C. exiguum Gmelin 
for more than a century (Petersen & Russell, 1971a). The nomenclatural problems 
within this genus have already been dealt with by us at this Congress; however, it 
should be noted that the present nomenclature is based on the acceptance of C. 
aculeatum L. as the type species of the genus name Cardium (Lamarck, 1799). 

It will be shown that by the combination of field observations, laboratory tolerance 
tests and field transplant experiments considerable insight may be gained into the 
taxonomic and ecological interrelationships of the species. 

MATERIALS AND METHODS 

Our studies involved Cardium edule L., C. glaucum, C. exiguum and C. hauniense 
Petersen & Russell (1971a), which were identified using the methods of Petersen (1958), 
Russell (1969) and Petersen & Russell (1971b). 

Detailed accounts of the methods involved may be seen from Russell (1969) and thus 
only a brief summary will be given. The preferred habitat of each species was found 
by measuring parameters, such as salinity, temperature, exposure, exposure to air, 
tidal amplitude, etc., of the environments of many populations covering as wide a 
geographical range as possible. The tolerances of the species to those parameters 
which may be limiting their distributions were tested under controlled laboratory 
conditions, using samples from populations having similar environmental histories; 
populations consisting of 2 species were used frequently for direct comparisons thus 
avoiding non-genetic adaptations (Kinne, 1964). To test the conclusions reached from 
the laboratory tests, large numbers of cockles were transplanted to sites differing 
only in certain required respects and their survival recorded. If the transplanted 
cockles grew they provided a unique opportunity to check the validity of the use of 
certain shell features by taxonomists wishing to separate the species. 

RESULTS 

Field observations: From our field observations the preferred habitats of the 4 species 
(Table 1) show marked differences. 

Laboratory tolerance tests: The type of information gained from tolerance tests can 
be seen from the following results: 



1 Portsmouth Polytechnic Marine Laboratory, Ferry Road, Hayling Island, Hants, POllODG, U.K. 
2 University Zoological Museum, Univers itetsparken, 15, Copenhagen. Denmark. 

(223) 



224 PROC. FOURTH EUROP. MALAC. CONGR. 

TABLE 1. The habitat preferences and habits of the species, based on field observations. 





C. edule 


C. glaucum 


C. exiguum 


C. hauniense 


Salinity range 
(°/oo) 


15 - 35 


4 - 100 


20 - 35 


8-12 


Temperature range 

(°c.) 


3-25 


0-32 


3-25 


0-25 


Exposure to air 
(as % time) 


0-40 


- 5 


0-5 





Habitat exposure 


Estuarine 


Lagoon 


Estuarine/ 
Lagoon 


Lagoon 


Tidal amplitude 
(m.) 


0.2 - 10 


Zero - 5 


Zero - 10 


Zero - 0.1 


Habit 


Buried in 


Buried or 


Attached 


Attached 




substrate 


on surface 


by byssus 


by byssus 



TABLE 2. The salinity tolerances of the species based on samples from various habitats. 











Salinity 


(°/oo) 












Tolerances 






Site 


Habitat 


Lower 


LS 50 


Upper LS 50 


c. 


edule 


Lille 
Strand 


20 


12.5 




38.5 


c. 


glaucum 


и 


20 


14.5 




39.5 


с. 


exiguum 


Portsmouth 


30 


24.0 




39.0 


с. 


hauniense 


Dybso 
Fjord 


11 


9.0 




13.0 


с. 


glaucum 


Orford 


10 


3.7 




30.5 


с. 


glaucum 


Etang de 


52 


22.5 




82.5 






l'Arnel 











RUSSELL and PETERSEN 



225 



TABLE 3. The upper lethal temperatures of 2 species under conditions of different seawater 
availability. 



Seawater availability 
(ml / day) 


Upper lethal temperature 
(LT 50 in °C.) 


С edule 


C. glaucum 


200 
1,000 


18.7 
31.4 


31.4 
32.2 



TABLE 4. The susceptibility of 2 Cardium species, originating from homogeneous and hetero- 
geneous populations, to 'cockle-water. ' 





Survival time (days) 


Susceptibility 


Tidal 

Amplitude 
(m) 


Membrane Filtered 
'Cockle-water ' 


Membrane Filtered 
'Seawater ' 


Control x 100 
Test 



С glaucum 



85.0 + 



93.8 + 



110 



C. glaucum 0.2 



47.8 



97.8 



204 



C. edule 



0.2 



53.8 



114.4 



213 



C. edule 



58.8 



87.0 



148 



Salinity . Table 2 shows the results of 3 comparative experiments. The salinities 
in which 50% of the sample died (LS 50 ) were read off from salinity/response curves 
constructed from the survivals of the cockles in various salinities after a given time. 
In contrast to Cardium edule and C. glaucum, between which no inherent difference in 
salinity tolerance can be seen, C. exiguum and C. hauniense exhibit markedly different 
salinity tolerances. The significance of the latter result can be seen from a compari- 
son with the overlapping tolerances of 2 populations of C. glaucum despite the fact 
that their environmental salinities differed to a greater extent. 

Temperature . Field observations suggested that Cardium edule was absent from 
areas liable to summer water temperatures in excess of 25°C. Temperature tolerance 
tests demonstrated this clearly (Table 3). However, in another test, in which more 
water was made available to the cockles, the upper LT 50 was markedly higher. Thus 
temperature was significant only in conjunction with seawater availability. 

Stagnation . From the field observations it appeared that Cardium edule, in contrast 
to C. glaucum, required a tidal amplitude in excess of 0.2 m, suggesting that the former 
required the removal from its vicinity of a toxic metabolite. To test this theory the 
survivals of samples of C. edule and C. glaucum from homogeneous and heterogeneous 



226 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLE 5. The survival and shell features of Cardium edule and С glaucum after transplanta- 
tion to different environments. 





Widewater lagoon 


Chichester harbour 




C. edule 


С . glaucum 


C. edule 


C. glaucum 


survival (%) 





70 


87 


96 


posterior shell 
margin 


crenulate 


straight 


crenulate 


almost 
straight 


internal ribbing 


present 


present 


absent 


absent 


Periostracum 
thickness 


thin 


thick 


thin 


thick 


Mean shell height 
(as % increase) 


16.7 


36.6 


48.2 


48.7 



TABLE 6. The geographical distribution of the species. (+ = present; - = absent) 





C. edule 


C. glaucum 


С exiguum 


С hauniense 


Eastern Baltic 


- 


+ 


- 


- 


Central Baltic 


- 


+ 


- 


+ 


Western Baltic 


+ 


+ 


- 


+ 


Kattegat 


+ 


+ 


+ 


- 


North Sea 


+ 


+ 


+ 


- 


Channel 


+ 


+ 


+ 


- 


North eastern 
Atlantic 


+ 


+ 


+ 


- 


Mediterranean 


- 


+ 


+ 


- 


Black Sea 


- 


+ 


+ 


- 



populations in seawater, in which C. edule had been living for a given time (cockle- 
water), were checked. The results (Table 4) demonstrated an inherent difference 
between the species; samples of С glaucum from stagnant (i.e., non-tidal) lagoon 
conditions are less susceptible to cockle-water than those from tidal waters, whereas 



RUSSELL and PETERSEN 



227 




\ 



9 m 

















в 




V 











л 1 





m 



tf 



1 '' г- 1 



PLATE 1 

A, Cardium glaucum, before; B, Cardium edule, before; C, Cardium glaucum, 18 months after 
transplanting to Langstone Harbour; D, Cardium edule, 18 months after transplanting to Lang- 
stone harbour. Scale = cm. 



228 



PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 1. Mean dry shell weight against the cube of mean shell height for transplanted Cardium 

edule (X) and С glaucum (O), at Ellenore ( ), a tidal mud flat, and Widewater ( ), a 

nontidal lagoon. 



samples of C. edule from less tidal waters are more susceptible than those from 
fully tidal estuaries. 

Field transplant experiments 

By careful site selection it is possible to test the validity of both the conclusions 
reached from the laboratory tests and the use of various features in the identification 
of the species. Considering the results of a transplant of samples of young Cardium 
edule and C. glaucum to 2 sites having approximately the same salinities and tempera- 
tures but different tidal amplitudes (Table 5), it can be seen that both the survival of 
the cockles and certain shell features are dependent more on the different environments 
than on the species themselves (PI. 1). Further information may be gained from a 
more quantitative approach; for example, from a graph of mean shell weight against 
the cube of shell height (Fig. 1) it can be seen that the slopes of the lines (i.e., the 
rates of increase of shell weight with shell height or shell thickness) of the 2 species 
are parallel at each site. Thus shell thickness is dependant to a marked extent on the 
environment and, consequently, associated features, like internal ribbing are of no 
value in the identification of C. edule and C. glaucum. 



RUSSELL and PETERSEN 229 

Geographical distribution 

Having predicted which environmental parameters are limiting the habitat occupa- 
tion of the species, their geographical distributions can be proposed (Table 6). The 
absence of a species from any large area, for example the Mediterranean, is impos- 
sible to prove but all the evidence to date agrees well with their suggested distributions 
(Russell, 1971). It is of interest that the range of each pair of closely related species 
almost covers the entire European coast. 

INTERSPECIFIC RELATIONSHIPS 

A close relationship between Cardium edule and C. glaucum is shown by the fol- 
lowing features: 

Hybridisation 

In the laboratory, hybrid larvae which are viable at least to metamorphosis have 
been reared from gametes originating from homogeneous populations (Kingston, verbal 
commun.). However, in nature apparent hybrids (i.e., cockles with shell characters 
intermediate between the species) represent only 2 or 3% of some heterogeneous 
populations. Boyden (1971) accounted for this by demonstrating a displacement of 
spawning times in a mixed population, Cardium glaucum following some weeks after 
C. edule. Kingston (verbal commun.) has shown that this displacement only occurs 
in mixed populations and Russell (in prep.) has shown that it occurs when a mixed 
population is created by transplantation. 

Character displacement 

In heterogeneous populations some morphological features of the shell in Cardium 
glaucum appear to exhibit the phenomenon of character displacement (Brown & Wilson, 
1956); for example: 

(a) Despite the larger variation of the mean rib number in Cardium glaucum (20.8- 
27.2) compared with that in C. edule (22.5-25.6) from homogeneous populations, data 
from mixed populations show that the mean rib number in C. glaucum is always sig- 
nificantly less than that in C. edule (Table 7). The mean rib numbers of each species 
from partly mixed and partly unispecific populations (Table 8) show that it is the mean 
rib number in C. glaucum which is displaced and not that in C. edule. 

(b) Some techniques for separating the species do not always hold good for the 
identification of individuals within unispecific populations, for example the ligament 
length/shell width ratio (Petersen, 1958). A shift in the plots representing Cardium 
glaucum towards those of C. edule occurs when data based only on unispecific popu- 
lations are compared with data based only on mixed populations (Russell, 1969). 

A close relationship between Cardium exiguum and C. hauniense is seen from their 
similar habits linked with the ability of the adult cockles to produce byssus; a feature 
not so far observed for any other Cardium species. No living mixed population has as 
yet been found, but it is proposed to investigate the possibility of hybridisation in the 
laboratory. 

CONCLUSION AND DISCUSSION 

From the field observations we conclude that each of the 4 Cardium species tends 
to occupy a different habitat, although each is capable of coexisting with at least 1 of 
the others; C. glaucum, the species tolerating the widest range of habitat, can coexist 
with all of the other species under various environmental conditions. It has been 



230 PROC. FOURTH EUROP. MALAC. CONGR. 

TABLE 7. Mean rib number in Cardium edule and C. glaucum from mixed populations. 



Origin 

of 
Sample 


Mean rib number 

(no. counted) 

C. edule C. glaucum 


Significantly 
different at 
P less than 


R. Roach 
estuary 


22.24 (62) 


20.58 (62) 


0.001 


R. Crouch 
estuary 


23.44 (35) 


21.79 (65) 


0.001 


Pughavn 


24.04 (57) 


23.28 (48) 


0.05 


0r¿ 


24.62 (50) 


23.04 (50) 


0.001 


Ve lier up 


24.10 (70) 


22.60 (162) 


0.001 


Nykobing 


23.75 (20) 


22.04 (46) 


0.001 


Lynaes 


23.75 (30) 


23.12 (36) 


0.05 


Jaegerspris 


24.25 (46) 


22.91 (30) 


0.001 



shown previously (Petersen & Russell, 1971b and Russell, 1972) that on both morpho- 
logical and ecological grounds Cardium edule and C. glaucum, and Cardium exiguum and 
C. hauniense, may be considered as 2 pairs of very closely related species or siblings. 

From the laboratory tolerance tests we conclude that the allopatric distributions 
of Cardium exiguum and C. hauniense are maintained by the marked difference in 
their salinity tolerances. The allopatric 3 part of the distribution of C. glaucum (i.e., 
the Mediterranean basin and the majority of the Baltic) is preserved by the inability 
of C. edule to tolerate a low tidal amplitude, especially at high temperatures, and not 
its relative stenohalinity as suggested most recently by Muus (1967). 

Over the sympatric 3 part of their distributions ecological isolation is almost com- 
plete; Cardium glaucum, being unable to occupy the typical estuarine environment 
of C. edule, possibly due to the inability of their larvae to withstand even moderate 
exposure (Kingston, verbal commun.) is limited to lagoon habitats. However, in habi- 
tats like the shallow semitidal Danish fjords where neither stagnation nor summer 
water temperatures are excessive the species can be found together. Under such 



3 Note that our usage of the term sympatric follows that of Kohn & Orians (1962) rather than that 
of its originator (Mayr, 1942). 



RUSSELL and PETERSEN 



231 



TABLE 8. Mean rib number in Cardium edule and C. glaucum in unispecific and mixed popula- 
tions at Pughavn and Vellerup. 



Locality 


Population 
Composition 


Mean rib number 
(no. counted) 


Significantly 
different at 
P less than 




Only C. edule 


23.68 (63) 


no sig- 


Pughavn 


Both C. edule 


24.04 (57) 


difference 








and C. glaucum 


23.28 (48) 


0.05 




Both C. edule 


24.11 (70) 


0.001 


Vellerup 


and C. glaucum 


22.60 (162) 








Only C. glaucum 


23.56 (50) 


0.001 



conditions hybridisation is reduced to a minimum by the displacement of the spawning 
time in C. glaucum (Boy den, 1971). Also under these conditions C. glaucum exhibits 
character displacement, emphasising the morphological differences between the 
species. 

Kohn & Orians (1962) pointed out that morphological character displacement may 
lead to the members of those populations sympatric with a closely related species 
being described as a distinct species. They cited the case of Agelaius bicolor 
Audubon, which was in fact A. phoeniceus from those areas where its distribution 
overlapped that of a sibling, A. tricolor, but nevertheless survived in the literature 
for over 50 years (Mailliard, 1910). Despite the fact that the character displacement 
in Cardium glaucum is nothing like so obvious as the plumage displacement in the 
male A. phoeniceus, similar invalid species, based on samples of Cardium glaucum 
taken from areas where this species is sympatric with С edule, have been erected 
(Russell, 1972); for example, Reeve (1845) distinguished C. lamarcki from C. 
belticum Beck and it was not until more than a century had passed that they were 
finally amalgamated by Petersen (1958). It should be noted that until quite recently 
taxonomic studies of these cockles were based on shells in museum collections rather 
than on freshly collected material and thus the large morphological variation in C. 
glaucum served to confuse rather than elucidate the problem of its taxonomic status. 
However, it is of interest that the partly sympatric siblings were resolved before the 
allopatric siblings C. exiguum and C. hauniense, exemplifying the fact that character 
displacement results in sympatric siblings differing more from each other than 
closely related allopatric species (Brown & Wilson, 1956). 

The suggestion by Purchon (1939) that transplant experiments would prove useful in 
the resolution of the taxonomic position of the 'varieties of Cardium edule' was indeed 
valid. However, it should be remembered that their use is limited to the study of 
siblings whose adults, at least, can coexist in the same habitat; thus with allopatric 



232 PROC. FOURTH EUROP. MALAC. CONGR. 

species the testing of their survivals in a number of different habitats may be an 
unrewarding prerequisite. 

Finally we suggest that this ecological approach, which has clarified the taxonomic 
position of these 4 Cardium species and accounted for their distributions, might well 
be applicable to other closely related species in this and other genera of marine 
bivalves. 

REFERENCES 

BOYDEN, С R., 1971, A comparative study of the reproductive cycles of the cockles 

Cerastoderma edule and C. glaucum. J. mar. biol. Assoc. U.K., 51: 605-622. 
BROWN, W. L. & WILSON, E. O., 1956, Character displacement. Syst. Zool., 2: 72-84. 
KINNE, О., 1964, Non-genetic adaptation to temperature and salinity. Helgolander 

wiss. Meeresunters., 9: 433-458. 
KOHN, A. J. & ORLANS, G. H., 1962, Ecological data in the classification of closely 

related species. Syst. Zool., 11: 119-127. 
LAMARCK, J. В., 1799, Prodrome d'une nouvelle classification des coquilles. Mém. 

Soc. hist, natur. Paris, 63-90. 
MAILLIARD, J., 1910, The status of the California bi-colored blackbird. Condor, 12: 

63-70. 
MAYR, E., 1942, Systematics and the origin of species. Columbia University Press, 

New York, 334 p. 
MUUS, B. J., 1967, The fauna of Danish estuaries and lagoons; Distribution and ecology 

of dominating species in the shallow reaches of the mesohaline zone. Meddr. 

Danm. Fisk. og Havunders., 5: 1-316. 
PETERSEN, G. H0PNER, 1958, Notes on the growth and biology of the different 

Cardium species in the Danish brackish water areas. Meddr. Danm. Fisk. og 

Havunders, 2 no. 22: 1-31. 
PETERSEN, G. H0PNER & RUSSELL, P.J.C., 1971a, Cardium hauniense, a new brack- 
ish water species from the Baltic. Ophelia, 9: 11-13. 
PETERSEN, G. H0PNER & RUSSELL, P. J. C, 1971b, Cardium hauniense compared 

with C. exiguum and C. glaucum. Proc. malacol. Soc. Lond., 39: 409-419. 
PURCHON, R. D., 1939, The effect of the environment upon the shell of Cardium edule. 

Proc. malacol. Soc. Lond., 23: 256-267. 
REEVE, L. A., 1845, Monograph of the genus Cardium. In: Conchologica Iconica, 2 

(1843), species 93 and 113. 
RUSSELL, P. J. C, 1969, Studies on the ecology, distribution and morphology of the 

cockles Cardium edule L. and C. glaucum Brug. Thesis, London Univ. 
RUSSELL, P. J. C, 1971, A reappraisal of the geographical distributions of the cockles 

Cardium edule L. and C. glaucum Brug. J. Conchol., 27: 225-234. 
RUSSELL, P. J. C, 1972, A significance in the number of ribs on the shells of two 

closely related Cardium species. J. Conchol., 27: 401-409. 



MALACOLOGIA, 1973, 14: 233-234 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE NOMENCLATURE AND CLASSIFICATION OF SOME EUROPEAN 
SHALLOW -WATER CARDIUM SPECIES 

G. H0pner Petersen 1 and Peter J. C. Russell 2 

ABSTRACT 

The nomenclature for the genus Cardium depends on the acceptance of the 2 following designations of 
type species: 

A. Cardium aculeatum, Linné 1758, selected by Lamarck 1799, accepted by Bucquoy Dautzenbere & 
Dollfus, 1892. 

B. Cardium costatum, Linné 1758, selectedby Children 1823, accepted by Kennard, Salisbury & Woodward 
1931. 

The 2 possibilities for nomenclature are demonstrated in Table 1. In this abstract we follow Bucquoy, 
Dautzenberg & Dollfus to retain the well known name Cardium. The 4 shallow-water species С edule 
C. glaucum, C. exiguum and С hauniense are placed in the same genus as C. aculeatum. Table 2 shows 
that morphological characters alone cannot allow grouping. C. aculeatum can be separated from the 4 
shallow-water species on the basis of size and vertical distribution. 

TABLE 1 

Taxon: v 

to be divided into 

Taxa: x - y - z 

Taxon x includes: 

larger species: Cardium aculeatum, C. tuberculatum, C. echinatum, С paucicostatum, С erinaceum. 
smaller species: C. papillosum, C. minimum, C. ovale, C. scabrum, С parvum, C. simile, 
(C. elegantulum), (C. pinnatulum). 

Taxon у includes: 

C. edule, C. glaucum. 

Taxon z includes: 

C. exiguum, C. hauniense. 

The nomenclature of these taxa depends on the type-species designation for the genus Cardium. Two 
possibilities exist: 

A. C. aculeatum is the type-species, then 
v = Cardium sensu latu 

x = Cardium s.S., y = Cerastoderma, z = Cerastobyssum. 

B. C. costatum is the type-species, then 
v = Cerastoderma sensu latu 

x = Acanthocardia, y = Cerastoderma s.S., z = Cerastobyssum. 

Note for the x taxon. 

This taxon is a pool, which we at present can only group into the larger and the smaller species. It 
includes the Cardium aculeatum, which is the type -species of Acanthocardia and eventually also of Cardium. 
We do not consider the 2 north and northwest Atlantic species elegantulum and pinnatulum (see Clench, 
W. J. & L. С Smith, 1944: The family Cardidae in the western Atlantic. Johnsonia, 1(13): 32 p, p 12) to 
be included into our у taxon (= Cerastoderma). 

Note for the у taxon. 

It is of no doubt that Cardium edule is the nominal type-species for the genus name Cerastoderma, Poli. 

Note for the z taxon. 

None of the 2 species included have been designated as type-species for a genus. However the name 
Cardium exiguum is in trouble with the genus Parvicardium (see Petersen, G. H0pner & Peter J. C. Russell, 
1972, A proposed termination to the widely accepted junior synonymy of Cardium parvum Phillippi to С 
exiguum Gmelin. J. Conchol., 27: 397-400). We call the z taxon Cerastobyssum and designate C. hauniense 
to be the type-species for Cerastobyssum. 



1 Zoological Museum, Copenhagen, Denmark 

2 Marine Laboratory, Hayling Island, Hants, England 

(233) 



234 



PROC. FOURTH EUROP. MALAC. CONGR. 
TABLE 2 



C. exiguum C. hauniense C. glaucum 



C. edule 



C. aculeatum 



Shell characters: 
furrowed ribs 
projections on ribs 
thick periostracum 
raised ligament 
keeled shell 
rib number 
max. length, mm 
no. of teeth in right hinge: 

anterior 

cardinal 

posterior 
Ecological characters: 
S% tolerance in % 
habitat preference 
use of byssus by adults 
horizontal distribution 
vertical distribution in m 
occurs with 
larval development 
Other characters: 
nice electrophorese 
tailing electrophorese 
has been confused with 
was type designated for 



knots 



knots-spines 



scales 



'steps" knots-spines 



20-22 


23-30 


17-32 


19-29 


20-22 


15 


10 


50 


60 


100 


2 


1 


2 


2 


2 


2 


2 


2 


2 


2 


1 


1 


2 


2 


1 


25-35 


6-12 


3-100 


15-35 


? 


tidal -lagoon 


lagoon 


lagoon 


tidal 


? 


+ 
Mediterr.- 
Norway 

0-55 


+ 
Baltic 
0-40 


(+) 
Mediterr.- 
Norway 

0-50 


Morocco- 
Iceland 
0-10 


? 
Mediterr.- 
North Sea 
50-2000 


gl. ed. 


gl. 


ex. ha. ed. 


ex. gl. 


? 


egg capsules 


egg capsules 


free spawning 


free spawning 


? 


_ 


+ 


_ 


- 


? 


+ 


_ 


+ 


_ 


? 



ex. gl. ex. ed. 

Cardium 
Parvicardium Cerastobyssum Parvicardium Cerastoderma . .. ,. 

J Acanthocardia 



(ex. = C. exiguum; ha. = C. hauniense; gl. = С. glaucum; ed. = С. edule; ас. = С. aculeatum.) 



Table 1 presents a proposed classification of the cockles (Cardiidae) living in the Mediterranean Sea, 
the Baltic Sea and the coastal waters from Greenland to Spain; however the Caspian Sea is excluded and 
thus Didacna, Monodacna and Adacna are not considered. 

For the shallow-water Cardium species, Table 2 demonstrates that by use of any particular character 
it is possible to pair up almost any combination of 2 species. Two groups are formed, 1 based on pre- 
sence of 2 posterior lateral teeth in the right valve (edule + glaucum) and 1 based on the adults climbing with 
a byssus (exiguum + hauniense). 

REFERENCES 

BUCQUOY, E., DAUZENBERG, Ph. & DOLLFUS, G., 1887-1898, Les Mollusques marins du Roussillon, 

2, Pélécypodes, 884 p, Paris. 
CHILDREN, J. G., 1823, Lamarck's genera of shells. Q. J. Sei. Lit. Arts. Lond., 14: 298-322. 
KENNARD, A. S., SALISBURY, A. E. & WOODWARD, В. В., 1931. The types of Lamarck's genera of shells 

as selected by J. G. Children in 1823. Smithson. misc. Collect., 82(17): 40 p, 2. 
LAMARCK, J. В., 1799, Prodrome d'une nouvelle Classification des Coquilles. Mém. Soc. Hist, natur. 

Paris, p 63-90. 
PETERSEN, G. H0pner & RUSSELL, P. J. C, 1971, Cardium hauniense compared with С. exiguum and 

С. glaucum. Proc. malacol. Soc. Lond., 39: 409-420. 



MALACOLOGIA, 1973, 14: 235-241 

PROC. FOURTH EUROP. MALAC. CONGR. 

A PRELIMINARY REPORT ON SYSTEMATICS AND DISTRIBUTION OF THE 
GENUS ERVILIA TURTON, 1822 (MESODESMATIDAE, BIVALVIA) 

Louise A. de Rooij-Schuiling 

Rijksmuseum van Natuurlijke Histoire, Leiden, Netherlands 

INTRODUCTION 

This is a preliminary report on the systematics and distribution of the genus Ervilia. 
A more extensive and documented revision of all the species of the Mesodesmatidae 
will be published later (De Rooij-Schuiling, 1974). 

The species of the genus Ervilia, created by Turton in 1822, have typical meso- 
desmatid characters, viz., the possession of a feeble outside ligament, a strong resi- 
lium and the structure of the hinge. Their distribution is tropical and subtropical. 

DIAGNOSIS OF THE MESODESMATIDAE 

The Mesodesmatidae have equivalved shells from a small to moderately large size 
(max. length 3-140 mm) and of a subtriangular, ovate or subtrigonal-inequilateral 
shape. The umbones are mostly posterior. The external ligament is short and feeble, 
but there is a stout resilium fitted in a deep resilifer. The hinge is rather solid. In 
each valve a single cardinal is present. In the left valve there is 1 lateral on each 
side of the umbo fitting between the 2 opposite laterals of the right valve. The palliai 
sinus is variously developed, even absent in some genera. 

TAXONOMY OF THE GENUS ERVILIA TURTON, 1822 

Ervilia Turton, 1822: 55. Type species Mya nitens Montagu, 1808: 165. 
Rochefortina Dall, 1924; 88. Type species R. semele Dall, 1924: 88. 
Spondervilia Iredale, 1930: 402. Type species Ervilia australis Angas, 1877: 175, 
pi. 26, fig. 21. 

Dall first described in 1924 a tiny shell from Oahu. He placed it in Rochefortina, 
a new subgenus of Rochefortia, and named it R. semele. In 1938 he synonymized this 
species with Ervilia sandwichensis Smith, 1885, thereby raising Rochefortina to a genus. 
R. sandwichensis is, however, a species which differs only on specific level from its 
nearest relative, Ervilia bisculpta Gould, 1861. So Rochefortina Dall, 1924 becomes a 
junior subjective synonym of Ervilia Turton, 1822 (De Rooij-Schuiling, 1972). 

In 1930 Iredale created the new genus Spondervilia for the Ervilia' s from the 
Australian area. This genus was based on Ervilia australis Angas, 1877 as type species. 
However, contrary to Iredale' s views, Ervilia australis and E. bisculpta are con- 
specific, and there is no difference between the specimens of the Australian and the 
Japanese populations. Because E. bisculpta differs only on the species level from 
other Ervilia's, Spondervilia Iredale, 1930 is a junior subjective synonym of Ervilia 
Turton, 1822 (De Rooij-Schuiling, 1972). 

DIAGNOSIS OF THE GENUS ERVILIA 

Small mesodesmatids (max. size of recent species: length 15 mm; height 9 mm). 
Shell elongate-ovate to triangular, mostly inequilateral. Umbo on the anterior side. 

(235) 



236 PROC. FOURTH EUROP. MALAC. CONGR. 

The dorso -anterior side is straight to slightly convex, anterior, ventral and posterior 
sides are rounded. Some species have white, others coloured shells; the periostracum 
is nearly always completely worn off. The surface can be smooth and glossy with 
concentric growth lines only, or it can have distinct concentric ridges. But in all 
species radial sculpture is present, although in some species only on very few speci- 
mens. Although denied by some authors (Lamy, 1914: 12; Davis, 1967: 233), the 
Ervilia's do have 2 lateral teeth in the right valve. The palliai sinus is deep and the 
palliai line is looped posteriorly on the ventral side of the sinus (see Fig. 5). 

DISTRIBUTION OF THE GENUS 

Ervilia seemed to appear suddenly in Europe during the Eocene. Their fossils 
are found in many of the sediments of the Thetys Sea: in Poland, Austria, France, 
North Italy and even in South Italy. The distribution of the fossils is mostly along 
the margin of the distributional area of the Recent species. It is strange to notice 
that they do not occur in the Mediterranean in recent times. I have as yet no explana- 
tion for this phenomenon. They have a really good adaptability, as is evident by their 
occurence in both the Atlantic Ocean and the Red Sea. 

Ervilia nitens (Montagu, 1808) (Figs. 1 and 5) 

Mya nitens Montagu, 1808: 165. 

Ervilia nitens (Montagu); Turton, 1822: 56, pi. 19, fig. 4. 

Ervilia concéntrica Gould,* 1862: 281. 

Ervilia subcancellata Smith, 1885: 80, pi. 6, fig. 2-2b. 

Ervilia maculosa Dall, 1896: 26. 

Ervilia califomica Dall, 1917: 414. 

Ervilia rostratula Rehder , 1944: 189, pi. 19, fig. 1-2. 

* Holmes described in 1860 a fos s il Ervilia and named it Mesodesma concéntrica. 
According to Davis (1967) it is conspecific with Ervilia concéntrica Gould. I 
do not want to express an opinion now because I have not yet made a thorough 
study of the fossils. 



Diagnosis: 

Medium sized Ervilia (max. length 9 mm, height 6 mm). Shell ovate to triangular. 
The appearance of the apex is variable. Sometimes, especially in pink specimens, the 
outline is rounded, hardly disturbed by the umbo. Sometimes the umbo projects 
conspiciously. All intermediate forms do occur. Shell white to pink. Concentric 
ridges all over the shell. If radial sculpture is present it is distinct but not as deep as 
the concentric ridges. Radial sculpture is mostly only present on the posterior side; 
however, sometimes it is found on the anterior side as well. 

Remarks: 

Ervilia nitens was first described from specimens found in Durban, Scotland. These 
few valves are so often mentioned in the literature that the species is considered 
British by many authors, even recently. I think, however, that Forbes & Hanley 
(1853: 345) were probably right in supposing that sailing ships brought them from the 
West Indies in their ballast sand which they put down in the Scotch harbour, thereby 
bringing these Caribbean molluscs to places far from their habitat. 

The species is so very pluriform that it was described as 6 species. The synonymy 
of Ervilia maculosa with E. concéntrica, and of E. rostratula with E. subcancellata, 



DE ROOIJ-SCHUILING 



237 












FIGS. 1-6. Ervilia species. FIG. 1. Ervilia nitens. Left valve of type specimen of E. califor- 
nien. San Pedro, California. Nat. size: 6. 5 mm long, 4. 5 mm high. FIG. 2. Ervilia castanea. 
Right valve. Portinho, Portugal. Nat. size: 12 mm long, 7 mm high. FIG. 3. Ervilia scaliola. 
Left valve. Ras Matarma, Red Sea. Nat. size: 6 mm long, 3. 5 mm high. FIG. 4. Ervilia Ы- 
sculpta. Right valve. Shionomisaki, Japan. Nat. size: 4. 6 mm long, 3. 2 mm high. FIG. 5. 
Ervilia nitens. Innerside left valve of type specimen of E. maculosa. Cape Lookout, North Car- 
olina. Nat. size: 4. 7 mm long, 3. mm high. FIG. 6. Ervilia sandwichensis . Right valve. 
Oahu, Sandwich Islands. Nat. size: 3. mm long, 2. 3 mm high. 



had also occurred to J. D. Davis (pers. comm., 1969). The study of the type specimens 
and of great amounts of material of this species from localities all over the western 
part of the Atlantic Ocean has convinced me that there is only 1 species in that region 
(Chart 1). 



238 PROC. FOURTH EUROP. MALAC. CONGR. 

Ervilia castanea (Montagu, 1803) (Fig. 2) 

Donax castanea Montagu, 1803: 573, pi. 17, fig. 2. 
Capsa castanea, Turton, 1822: 128, pi. 10, fig. 13. 
Ervilia castanea, Chenu, 1843: 3. 

Diagnosis: 

Large Ervilia (max. length 12 mm, height 6 mm). Shell elongate -ovate, mostly 
inequilateral. The dorsal posterior side is mostly slightly concave. The valves are 
light brown. The pigmentation of the shell is often radial. The smooth surface is 
glossy and has concentric growth lines only. A few specimens have a distinct but 
very shallow radial sculpture as well. 

Remarks: 

The material I have seen of this species suggests that it has its relict distribution 
around the Azores. I think this may be the only Recent habitat, whereas material 
found in other localities has been brought there by sea currents (Chart 1). 

Ervilia scaliola Issel, 1869 (Fig. 3) 

Ervilia scaliola Issel, 1869: 53, pi. 1, fig. 2. 
Ervilia purpurea Deshayes, manuscript name. 

Diagnosis: 

Large Ervilia (max. length 15 mm, height 9 mm). Shell elongate-ovate, mostly 
inequilateral. The dorsal posterior side is mostly slightly concave. The shells are 
white to deep purple. The colour of the shell has mostly a radial pattern. The surface 
is mostly smooth with growth lines only and sometimes superficial radial structure. 
Some specimens have concentric ridges and obvious radial sculpture on both the 
anterior and posterior sides. 

Remarks: 

This species lives mostly in sea water with an extremely high salinity, viz., about 
45%o in the Red Sea and up to 55% in parts of the Persian Gulf. The shells from these 
areas are almost invariably smooth with growth lines and very superficial radial 
sculpture only. Specimens from the only locality with a lower salinity known to me, 
viz., Karachi have obvious concentric and radial sculptures (Chart 1). 

Ervilia bisculpta Gould, 1861 (Fig. 4) 

Ervilia bisculpta Gould, 1861: 28. 

Ervilia livida Gould, 1861: 28. 

Ervilia japónica Adams , 1862: 224. 

Ervilia australis Angas, 1877: 175, pi. 26, fig. 21. 

Ervilia ambla Dali, Bartsch & Rehder, 1938: 171, pi. 44, fig. 5-8. 

Diagnosis: 

Small Ervilia (max. length 7 mm, height 4 mm). Shell elongate -ovate to triangu- 
lar, often equilateral. Anterior and posterior dorsal margins straight to slightly con- 
vex. The shells are white, often with an ivory shade. Concentric ridges all over the 
surface and very deep radial sculpture on both the anterior and posterior sides. 

Remarks: 

The study of type specimens and of material from many localities has convinced me 
that the species Ervilia livida, E. japónica, E. australis and E. ambla are conspecific 



DE ROOIJ-SCHUILING 



239 




CHART 1. %Ervilianitens, %Ervilia nitens, dubious loe. ^Ervilia castanea, MErvilia scaliola. 
CHART 2. %Ervïlia bisculpta, %Ervïlia sandwichensis . 



240 PROC. FOURTH EUROP. MALAC. CONGR. 

with E. bisculpta. The species has a much wider distribution than formerly was 
assumed. In the localities near the Seychelles and Amirante Islands it approaches the 
area of E. scaliola, thus forming a more or less continuous area of distribution for the 
genus (Chart 2). 

Ervilia sandwichensis Smith, 1885 (Fig. 6) 

Ervilia sandivichensis Smith, 1885: 81, pi. 25, fig. 5-5b. 
Rochefortia (Rochefortina) semele Dall, 1924: 88. 
Rochefortina sandivichensis Dali, Bartsch & Rehder, 1938: 169. 

Diagnosis: 

Tiny Ervilia (max. length 3 l/2 mm, height 2 l/2 mm). Shell rounded ovate. The 
posterior side is somewhat expanded in the dorsal direction, thus forming a small 
cavity in the posterior dorsal margin, near to the umbo. Because of this the dorsal 
laterals do not quite reach the umbo. The umbo projects distinctly from the dorsal 
side. The surface of the white valves has both deep concentric ridges and deep radial 
sculpture all over the shell. 

Remarks: 

This rare species is only known from the Sandwich Islands and Japan (Chart 2). 

Principal localities 

Ervilia nitens: Dunbar, Scotland; St. Helena; Fernadez de Noronha; Dutch Guyana; 
St. Martin, Antilles; Guadeloupe; Barbuda; Lake Worth; Bermuda; San Pedro, 
California. 

Ervilia castanea: Falmouth; Treen; Porthcurno; Scilly Islands; Roscoff; Portinho; 
Setubal; Canaries; Azores. 

Ervilia scaliola: Karachi; Persian Gulf; Gulf of Bahrein; Djibouti; Dahlak; Ras Matarma; 
Gulf of Akaba; Bitter Lakes. 

Ervilia bisculpta: Mast Head Island; Port Jackson; New Caledonia; Society Islands; 
Sandwich Islands; Shionomisaki; Kagoshima; Philippines; Gulf of Thailand; Sey- 
chelles; Amirante Islands. 

Ervilia sandwichensis: Honolulu; Shionomisaki. 

ACKNOWLEDGEMENTS 

This study was partly made possible by grants from The Netherlands Foundation for 
the Advancement of Tropical Research (WOTRO), The Royal Netherlands Academy of 
Sciences and The Ter Pelkwijk Fund. 

REFERENCES 

ADAMS, A., 1862, On some new species of acephalous Mollusca from the Sea of Japan. 

Ann. Mag. natur. Hist., Ser. 3, 9: 223-230. 
ANGAS, G. F., 1877, Descriptions of one genus and twenty-five species of marine 

shells from New South Wales. Proc. zool. Soc. Lond., p 171-177, pi. 26. 
CHENU, J. -С, 1843, Hlustrations Conchyliologiques. Paris. 
DALL, W. H., 1896, On the American species of Ervilia. Nautilus, 10(3): 25-27. 
DALL, W. H., 1917, Diagnosis of a new species of marine bivalve mollusks from the 

northwest coast of America in the collection of the United States National Museum. 

Proc. U. S. natn. Mus., 52: 393-417. 
DALL, W. H., 1924, Notes on molluscan nomenclature. Proc. biol. Soc Wash., 37: 87- 

90. 



DE ROOIJ-SCHUILING 241 

DALL, W. H., BARTSCH, P. & REHDER, H. A., 1938, A manual of the Recent and fos- 
sil marine pelecypod mollusks of the Hawaiian Islands. Bull. Bernice P. Bishop 

Mus., Honolulu, 153: 1-233, pis. 1-58. 
DAVIS, J. D., 1967, Ervilia concéntrica and Mesodesma concéntrica: clarification of 

synonymy. Malacologia, 6(1-2): 231-241. 
FORBES, E. & HANLEY, S., 1853, A history of British Mollusca and their shells, 

Vol. 4. London, 301 p, 133 pis. 
GOULD, A. A., 1861, Descriptions of shells collected by the North Pacific Exploring 

Expedition. Proc. Boston Soc. natur. Hist., 8: 14-40. 
GOULD, A. A., 1862, Descriptions of new genera and species of shells. Proc. Boston 

Soc. natur. Hist., 8: 280-285. 
IREDALE, T., 1930, More notes on the marine Mollusca of New South Wales. Rec. 

Austr. Mus., 17: 384-407, pis. 62-65. 
ISSEL, A., 1869, Malacologia del Mar rosso, ricerche zooligiche e paleontologiche. 

Pisa, 387 p, 5 pis. 
LAMY, E., 1914, Revision des Mesodesmatidae vivants du Muséum d'Histoire naturelle 

de Paris. J. Conchyliol., 62: 1-74, 1 pi. 
MONTAGU, G., 1803, Testacea Britannica. London, 606 p, 16 pis. 
MONTAGU, G., 1808, Testacea Britannica, Supplement. London, 183 p, pis. 17-30. 
REHDER, H. A., 1944, New marine mollusks from the Antillean region. Proc. U.S. 

natn. Mus., 93(3161): 187-203, pi. 19. 
DE ROOIJ-SCHUILING, L. A., 1972, Zool. Meded., Leiden, 46(5): 55-68, figs. 1-6. 
DE ROOIJ-SCHUILING, L. A., 1974, Zool. Verh., Leiden, In press. 
SMITH, E. A., 1885, Report on the Lamellibranchiata collected by H.M.S. Challenger 

during the years 1873-1876. Rep. sei. Res. Voy. Challenger, Zool. XIH part 35, 

341 p, 25 pis. 
TURTON, W., 1822, Conchylia Insularum Britannicarum. Exeter, p i-xlvii + 1-279, 

20 pis. 



MALACOLOGIA, 1973, 14: 242-243 

PROC. FOURTH EUROP. MALAC. CONGR. 

DIE GATTUNG MELANOPSIS FERUSSAC 1807 AUF NEUKALEDONIEN 

Ferdinand Starmtlhlner 

1. Zoologischen Institut der Universität Wien, Österreich 

ZUSAMMENFASSUNG 

Die Gattung Melanopsis ist rezent einerseits von den Küstenländern des Mittelmeeres (mit verwandten 
Gattung, z.B. Fagotia und Amphimelania auch an Reliktstandorten in Mittel- und Südsteuropa) bis nach Iran, 
andererseits im Südwestpazifik in Neukaledonien und Neuseeland verbreitet. Nach Sunderbrinck (1929) 
dürften sich die Cerithiidae und Thiaridae (=Melaniidae) im unteren Trias von ausgestorbenen Pseudo- 
melaniidae ableiten. Im oberen Jura dürfte es schliesslich zur Aufspaltung der rezent rein marinen Ceri- 
thiidae und der rezent brackisch oder limnisch lebenden Thiaridae gekommen sein. Am Übergang zwischen 
Kreide und Tertiär spalten sich die Melanopsinae von den übrigen Thiaridae ab, wobei es zum Übergang 
von marinen Litoralformen zu Brackwasser-bzw. Süsswasserformen gekommen sein dürfte. Zahlreiche 
Melanopsis -Arten, darunter auch die neukaledonischen Arten, zeigen auch heute noch eine Toleranz zu 
Brackwasser, d.h. sie sind von reinen Süsswasserabschnitten der Flüsse bis zu den brackischen Flut- 
rückstaugebieten anzutreffen. 

Nach Bubnoff (1956) bildete im Alttertiär das äquatoriale Mittelmeer noch einen durchlaufenden Gürtel 
von Mexiko über Gibraltar und den Südsaum Eurasiens bis zu den Sunda-Inseln, Neuguinea und Neuseeland, 
wobei alte Massive die Tethys in einzelne Stränge zerlegte. In dieser Zeit wird von den Geologen auch die 
Auffaltung von Neukaledonien aus marinen Sedimenten der papuanischen Geosynklinale von Neuguinea bis 
Neuseeland zwischen Australien und dem allmählich im Meer untertauchenden Tasmania-Kontinent ange- 
nommen (Le Borgne, 1964). Es ist daher möglich, dass dabei, die im Küstensaum der Tethys von 
Eurasien vorkommenden Melanopsiden in eine neuseeländisch - neukaledonische, bzw. mediterran-vorder- 
asiatisch Gruppe aufgespalten wurden. 

Die langzeitige Isolierung der Gattung auf Neukaledonien führte bei der Variabilität der Schalengrösse, 
-form, und -färbung zur Ausbildung zahlreicher Schalenvarietäten, die von den älteren Konchyliologen als 
eigene Arten beschrieben wurden. Bei der Durchsicht der Arbeiten von Morelet, Gassies, Crosse und 
Reeve findet man über 25 neukaledonische Arten beschrieben. Bereits Brot (1874) fasste diese Arten in 
seiner Monografie über die Melaniaceen auf drei Gruppen, die Melanopsis frustulum Morelet 1856/57- 
Gruppe, die Melanopsis brevis Morelet 1857-Gruppe und die Melanopsis mariei Crosse 1869-Gruppe 
zusammen. Pérès (1945/46) und Franc (1956) beliessen nach dem Studium des Schalenmaterials im Pariser 
Museum 6, bsw. 7 Arten für Neukaledonien. 

Nach den Serienaufsammlungen der Österr. Neukaledonien-Expedition 1965 und anatomischen Studien 
lassen sich auf Neukaledonien zwei Arten, Melanopsis frustulum und M. {Ze melanopsis) mariei aufstellen, 
wobei erstere, mit stark variabler Schale, in 6 verschiedene Formen zerfällt, die aber durch deutlich 
Übergänge verbunden sind. Anatomisch lassen sich die Formen nicht unterscheiden, ja es ist kaum möglich 
deutliche anatomische Unterschiede zu den mediterranen Arten zu finden (Starmühlner, 1970). So besitzen 
die neukaledonischen Melanopsis-Arten wie alle bisher untersuchten mediterranen, bzw. iranischen Arten 
sowohl beim o_ als beim <J eine off ene Genitalrinne, die von einer hohen Falte überdeckt wird, in der rechten 
äussersten Mantelbodenhälfte. Das Weibchen besitzt eine drüsige Laichgrube (Ovipositor) am Übergang 
zwischen Mantelhohlenboden in die äussere Fussf lache. Der Medianzahn der Radula zeigt bei M. frustulum 
die Formel 2/3+1+2/3, der Lateralzahn 1/2+1+1/2, innerer Marginalzahn mit 4-5, äusserer Marginalzahn 
mit 4, seltener 5 kleinen Dentikeln. Bei M. (Zemelanopsis) mariei ist die Zahl der Nebendentikel des 
Lateralzahnes etwas grösser, die Formel lautet demnach 2/3+1+4/5, äusserer Marginalzahn mit 5, innerer 
Marginalzahn mit 6 Dentikeln. Die Radula entspricht bei M. {Zemelanopsis) mariei mehr der neuseeländ- 
ischen M. {Zemelanopsis) trifasciata, der die Art auch in der Schalenbildung, mit rasch zunehmenden 
Umgängen, sehr nahe kommt. 

Im Anschluss an Pérès (1945/46) wurden 6 Formen von Melanopsis frustulum nach forma (Form und 
Grösse der Schale), modus (Art und Höhe des Gewindes) sowie coloratus (Färbung) unterschieden. 

1) M. frustulum f. normalis {-cylindrus), m. normalis-corrosus, col. maculatus 

2) M. frustulum f. normalis {-curta), m. normalis-corrosus, col. fasciatus 

3) M. frustulum f. normalis -curta, m. minor -corrosus, col. fasciatus 

4) M. frustulum f. normalis -cylindrus, im normalis-corrosus, col. multistriatus 

5) M. frustulum f. normalis -cylindrus, m. normalis-corrosus, col. fasciatus (et fuscus) 

6) M. frustulum f. curta-cylindrus, m. minor -corrosus, col. fasciatus 

Die ersten zwei Formen sind durch deutliche Übergänge verbunden und besiedeln die Urwaldbäche und 
-flüsse der zentralen Gebirge, die gegen die West, bzw. Ostküste abfliessen. Die 3. Form ist eine Zwerg- 
bzw. Kümmerform der 2. Form und findet sich isoliert ausschliesslich in zwei kleinen Seen (Lac en 8 und 
Grand Lac) in der Hochebene des südlichen Serpentingebietes in Gewässern mit äusserst geringem Mineral - 
salz-und Nährstoffgehalt (El 2 o:56 Mikro-Siemens) Die Formen 4-6 sind durch Übergänge verbunden und 
die subzylindrische Ausbildung des letzten Umganges gekennzeichnet. Es finden sich aber auch Übergänge 
zu den Formen 1-3 mit mehr spindelförmigem letztem Umgang. Sie besiedeln ausschliesslich die Unter- 
läufe, bzw. Mündungsgebiete der Bäche und Flüsse und finden sich häufig, wenigstens zeitweise, in Brack- 

(242) 



STARMÜHLNER 243 

wasser. 

Melanopsis (Zemelanopsis) mariei wurde nur in den Fliessgewässern im Süden Neukaledoniens im 
Bereich der Serpentin-Macchie gefunden. Am Rande von Urwald und Macchie tritt die Art in gemischten 
Populationen mit M. frustulum f. norm. -curta, m. norm.-corr., col. fasciatus auf. Die Arten lassen sich 
dabei leicht nach der Art der Zunahme der Windungen unterscheiden. Wie bereits erwähnt, steht mariei, 
nach der Form der Schale, der neuseeländischen Art M. (Zemelanopsis) trifasciata sehr nahe. 

LITERATUR 

BROT, A., 1874, In: MARTINI & CHEMNITZ, Syst. Conch. Cab., (1) 24, Melania, Bauer u. Raspe, Nürnberg, 

488 S. 
BUBNOFF, S. von, 1956, Einführung in die Erdgeschichte. Akademie Verl. München, 488 S. 
FRANC, A., 1956, Mollusques terrestres et fluviátiles de l'archipel Néo-Calédonien. Mem. Mus. natn. 

Hist, natur., Sir. A, Zool. 13, 200 S. 
PERES, J.M., 1945/46, Contribution à l'étude du genre Melanopsis. J. Conchyliol., 86: 109. 
STARMÜHLNER, F., 1970, Etudes hydrobiologiques en Nouvelle-Calédonie (Mission 1965 du Premier 

Institut de Zoologie de l'Université de Vienne) Die Mollusken der neukaledonischen Binnengewässer. 

Cah. O.R.S.T.O.M., sér. Hydrobiol., 4(3/4): 3. (Hier ausführliche Literaturzitate über die Melanopsiden 

Neukaledoniens). 



MALACOLOGIA, 1973, 14: 244-246 

PROC. FOURTH EUROP. MALAC. CONGR. 

ON A POLYPLACOPHORA DESCRIBED BY MONTEROSATO 

B. Sabelli 

Istituto di Zoología dell 'Univer sità, Bologna, Italia 

ABSTRACT 

About 2 years ago I began to review the Mediterranean Polyplacophora. During these studies I checked 
the types of "Chiton" {sensu lato) described by Monterosato. Thanks to the kind offices of Mr. Settepassi, 
whom I wish to thank, I was able to study the original specimens preserved in the Monterosato collection, 
now located in the Zoological Museum of Rome. This time I will describe only C. phaseolinus, 1 of the 4 
species of the Sicilian malacologist. Monterosato (1879) settled this species according to about 30 specimens 
from Arenella, a locality near Palermo (Sicily) (Fig. 1). Only a small number of these specimens are now 
in the author's collection, and another specimen, with a manuscript label of Monterosato, was given to him 
by A. Costa. I was able to study the species on the basis of cited specimens and also on about 10 others, 
corresponding to types (Figs. 2, 3) which were found by Dr. Spada and Prof. Franchini in 1968, 1969 and 
1970. So it was possible for me to examine isolated valves and microscopical preparations of perinotum. 

As already observed by Monterosato (1879), this species belongs to the genus Chiton. This is substan- 
tiated by 2 characters: its pectinate insertion plates and the thick rhomboid scales of perinotum. The 
esthetes also are typical of the genus Chiton. The shell is more narrow than in C. corallinus, with which 
it was often confused; it is not carinated, is on the average smaller (5-7 mm) than in the 2 congeneric 
species (C. olivaceus and C. corallinus) and is a pale green colour, sometimes with some whitish stains 
(the specific name phaseolinus is due to its colour). 

The tegmentum of intermediate and posterior valves (Fig. 4b, c) has 2 evident small elevated lateral 
areas. The sculpture is absent or sometimes is made up of 2-3 scars which are similar in shape to those 
of Callochiton achatinus. 

The articulamentum of the head valve has an insertion plate cut into a very variable number of pectinated 
teeth (8-14) (Fig. 4d), that of the posterior valve always has 8-9 teeth (Fig. 4f). The insertion plates of 
the intermediate valves (Fig. 4e) are divided into 2 teeth by an incision. The triangular apophyses (Fig. 
4b, c, e, f) extend medially to the point of nearly joining; they are like indentations in the jugal zone. 

The esthetes (Fig. 5) have an arrangement like those of Chiton olivaceus and C. corallinus: generally 
in the lateral areas there are about 8 micresthetes around an evidently larger megalesthete. In the median 
area the esthetes are more scarce than in the lateral areas and the size difference between micro-and 
megalesthetes decreases. 

Gills of the adanal type are present along the whole length of the foot. 

Dorsally the perinotum (Fig. 6a) has ellipsoid scales much more elongated than the ones of Chiton 
olivaceus and C. corallinus, and the scale surface is covered by a high number of ribs perpendicular to its 
major axis. Between these ribs there are irregular concentric wrinkles (Fig. 6b). A spiculose fringe is 
present and between the spicules we can observe long and subtle bristles like those described by Blumrich 
(1891) in the perinotum of C. olivaceus. 

The morphological characters now cited are, in my opinion, sufficient to confirm the validity of the 
species. In addition, there are ecological data which distinguish this species from its congeneric ones. In 
fact the specimens of Monterosato (1879), Costa and others I cited before were collected between 1 and 4 
meters depth. So it is clear that this species lives in shallow waters; on the contrary, Chiton corallinus, 
with which it is easily mistaken at a superficial analysis, lives in deeper waters (more than 15 m). 

On the basis of the 5 recent findings of Chiton phaseolinus, the distribution of this species is to be ex- 
tended to Lampedusa (Cala spugne, 1 specimen, 1968), Pantelleria (Scauri, 1 specimen, 1968), Camerota 
(Salerno, 2 specimens, 1969), Mazzarô (Taormina, 6 specimens, 1970), Capo de Gata (Southern Spain, 1 
specimen, 1970). The species probably lives in Italy on all coasts of Sicily and on the Tirrenic coast of 
Calabria and Campania. 

LITERATURE CITED 

BLUMRICH, T., 1891, Das integument der Chitonen. Z. wiss. Zool., 52: 404-476. 

MONTEROSATO, T. de, 1879, Enumerazione e sinonimia delle conchiglie mediterranee. Monografia dei 
Chitonidi del Mediterráneo. G. Sei. natur. econ. Palermo., 14: 1-23. 



FIG. 1. Specimen from the Monterosato collection (Arenella), 7x. FIG. 2. Specimen from Pantelleria 
(Scauri) legit Spada, 1968, 12x. FIG. 3. Specimen from Camerota (Salerno) legit Spada, 1969, lOx. FIG. 4. 
Isolated valves of a specimen from Mazzarô (Taormina), about 20x. a, dorsal view of the 1st valve; b, dor- 
sal view of the 4th valve; c, dorsal view of the 8th valve; d, ventral view of the 1st valve; e, ventral view of 
the 4th valve; f, ventral view of the 8th valve. 



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SABELLI 



245 




246 



PROC. FOURTH EUROP. MALAC. CONGR. 






6b 



0,2 m m 



FIG. 5. Esthetes of the lateral area. 

FIG. 6. a, Scales of the upper surface of the perionotum. b, Detail of a scale of the upper sur- 
face of the perinotum. 



MALACOLOGIA, 1973, 14: 247-270 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE SPECIES COMPLEX OF DIPLODON DELODONTUS (LAMARCK) 
(UNIONACEA - HYRIIDAE) 

J. J. Parodiz 

Carnegie Museum, Pittsburgh, Pennsylvania, U.S.A. 
ABSTRACT 

The relationships among 6 species of the genus Diplodon, belonging to the 
superspecific complex of D. delodontus (Lamarck), were studied to clarify their 
identification; a full conchological revision was made from which some species 
names, formerly placed in synonymy, were revalidated. The species here re- 
cognized are: Diplodon delodontus (Lamarck 1819); D. delodontus wymani (Lea 
1860); D. solisianus (d'Orbigny 1835); D. Uruguay ensis (Lea 1860); D. martensi 
(Ihering 1893); D. expansus (Küster 1856); and D. paulista (Ihering 1893). Their 
distribution includes the Paraná- Uruguay- La Plata river system in South Amer- 
ica (southern Brazil, northeastern Argentina and Uruguay); since such a system 
(as we know it today) did not exist before the Pleistocene epoch, the occupation 
of the area and process of speciation took place very rapidly and close to the 
Recent, which explains the great affinity still shown by the species. Many hy- 
brids within the populations were detected. Species sympatry, overlapping large 
portions of their areas of dispersion, precludes any subspecific treatment of the 
taxa (except in the case of D. delodontus wymani). Populations of different 
species are со- habitants of the same ecological niches; therefore the variations 
frequently found are not always phenotypical but rather genetical due to cross- 
breeding. The concept of superspecies is applicable to the D. delodontus group, 
being a monophyletic one of very closely related species, and their genetic affi- 
nities allow for recurrent hybridization. 

Species of the Diplodon delodontus group inhabit the middle and lower sections of 
the Paraná River, the Uruguay River and tributaries of the La Plata River system in 
South America, covering the areas of Southern Brazil, northeastern Argentina and 
Uruguay. In the present study, 6 species and 1 subspecies are recognized as belonging 
to this group or superspecies. 

In the abundant literature on the genus, the taxonomy included about 50 nominal 
taxa for the group. Names were given to individual variations, ecological forms, clines 
and especially various hybrids populations. Among the 7 recognized taxa, some "vari- 
ations" which appeared recurrently were identified as caused by crossbreeding; the 
lack of a prevalent evidence of allopatry in such intermediate forms precluded any 
subspecific consideration, except only in 1 case, of Diplodon delodontus wymani (Lea). 

Two or more different populations were found at short intervals at the same locus 
and ecological niches, and this not only renders it ineffectual to class them as 
"ecological forms," but actually they represented either different species or hybrid 
populations. 

As it has been demonstrated with other naiads from North America by a number of 
authors, and especially among the more recent ones, by Henry van der Schalie and 
David Stansbery, species which participate in environmental conditions of great 
similarity frequently show also similarity on their external characteristics, even 
when their relationships may be not too close, while at different locations one same 
species may have peculiarities of form, color or other shell characters, and can be 

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248 PROC. FOURTH EUROP. MALAC. CONGR. 

recognized clinally and ecologically. Such phenomenon obviously produced taxonomic 
confusion among the less known South American groups, a confusion which lasted many 
years. Sometimes, the differences found according to location are not simply pheno- 
typical; van der Schalie has shown (1941) that specimens transferred from their 
habitat in rivers to be reared in lacustrine environments, preserved the features of 
the former, and this is an indication that the characteristics have also a genetic 
constituency. 

Many of the named species of the genus Diplodon were placed in synonymy on embry- 
ological bases, i.e., by similarities of the glochidia. But the fact that 2 entirely dis- 
similar adult populations have larval stages that look alike is not an indication of 
conspecificity, because many of the characters with specific value may not become 
conspicuous until an advanced stage in the development of the individual. In well 
formed but still very young shells, differences can be detected which even when in 
their glochidial stage were undistinguishable. The great importance of glochidial 
identification is at the genus, subgenus or species-group level. 

Hybridization in mollusks is an occurrence which until recently received not enough 
attention. In gastropods, among which hybridization is even less known than among 
bivalves, several studies have recently dealt with the subject (e.g., the perfectly 
demonstrated hybridization by Owen, McLean & Meyer (1971) among several species 
of Haliotis from California). In bivalves, an interesting case of hybrid Tellina was 
disclosed by Boss. In freshwater bivalves, especially, their system of reproduction 
affords conditions very favorable to crossbreeding. In groups of species whose genetic 
constituency is of great affinity and monophyletic, and with populations largely sym- 
patric, hybridization may not only be feasible, but frequent. Masculine gametes of 2 
or perhaps more closely related species fertilizing a single female individual may 
result in offspring which are heterozygous as well as homozygous. 

For the purposes of identification, hybrids, as individuals or as populations, are 
recognized if the parental species involved are well known to the taxonomist in their 
most prevalent characteristics, as well as in their range of variation of distribution. 
Synonymies were usually made on second hand references, or analysis not careful 
enough, of original descriptions produced early last century, and this commentary is 
valid too for species which were created after 1900. 

The Diplodon delodontus group, with the complexity of its populations, leads us to 
the concept, which applies to it, of the superspecies. Simplifying other more elaborate 
definitions, the superspecies is a non-taxonomic (that is, not for nomenclatorial 
purposes) monophyletic group of very closely related species. The species recognized 
in our particular group are: Diplodon solisianus (d'Orbigny 1835), D. uruguayensis 
(Lea 1860), D. martensi (Ihering 1893), D. expansus (Küster 1856), D. paulista 
(Ihering 1893), D. delodontus (Lamarck 1819) and D. delodontus wymani (Lea 1860). 

The following hybrids, as individuals or populations, have been detected: 

Diplodon delodontus delodontus 
x D. solisianus 
x D. d. wymani 
x D. uruguayensis 
x D. martensi 

Diplodon uruguayensis 
x D. martensi 
x D. expansus 

Diplodon expansus 
x D. paulista 



PARODIZ 249 

Diplodon delodontus delodontus (Lamarck 1819); Figs. 1, 6, 7, 8 

Unio delodonta Lamarck, 1819: 77. Delessert, 1841: pi. 12, fig. 7. Catlow & 
Reeve, 1845: 58, No. 69. d'Orbigny, 1846: 605. Hupe, in Castelnau, 1857: 82. 
Formica Corsi, 1901: 449, No. 132. 

Unio delodon Martens , 1868: 193, 212. Strobel, 1874: 71. 

Unio delodontes Doering, 1875: 66 (Buenos Aires, Montevideo, Paraná", Cor- 
rientes). 

Unio delodontus Sowerby, in Reeve, 1864/67: fig. 288. Küster, 1861: 234, pi. 
88, fig. 5. Clessin, 1888: 171. Paetel, 1890: 150. 

Unio lacteolus Lea, 1834; 40, pi. 8, fig. 19 (and 1834 Observations: 152, pi. 8, 
fig. 19 - type loc. Rio de la Plata). d'Orbigny, 1835: 34 {ladeóla). Lea, 1867: 
22. Hiering, 1893:117. Ortmann, 1921: 518-523, 547, 548 (in part). Simpson, 
1914: 1227. Simpson and Ortmann used Lea's lacteolus because they consid- 
ered delodonta to be "unidentifiable. " Lea, subsequent to his description, 
compared ladeóla with the types of delodonta and declared them identical (see 
Synopsis 1836 y 1852). Also d'Orbigny, who apparently had access to La- 
marck's materials, identified his own collected specimens as delodonta. 

Unio divaricatus Lea, 1834a: 64, pi. 9, fig. 24 and 1934b: 176. 1870: 49, 116. 
Simpson, 1900: 878. Lea indicated divaricatus from Egypt! as Margarita 
(Unio) 1836, and Margaron (Unio) 1870. Catlow & Reeve, 1845: 58, No. 74. 

Unio rudus Lea, 1859: 187. 1860a: 16 (type loc. Rio de la Plata), 1860b: 84, 
pi. 43, fig. 146. Küster, 1861: 261, pi. 88, fig. 1. Doering, 1875: 45 (rudis, 
probably from Paetel, 1890). Diering, 1893: 117 (rudis). Simpson, 1900: 
875. U. rudus corresponds to the typical form oí Diplodon delodontus. 

Uniofirmus Lea, 1866: 33; 1868: 267, pi. 34, fig. 82; 1869: 27, 28, same figures 
(type loc. "South America": Uruguay River near Salto). 1870: 45 (as Margaron 
firmus). Hiering, 1893: 98, 105. Simpson, 1900: 875. Marshall, 1923: 4 
(as compared with podagrosus which is Uruguay ensis). Haas, 1916: 4. Bonet- 
to, 1961: 17 (as Diplodon). The named " Var. " firmus boettgeri Ehering, 
1893 = martensi (see Parodiz, 1968 and Mansur, 1970). 

Unio paraguay ensis Lea, 1866: 34; 1868: 271, pi. 35, fig. 85 and 1869; 31, same 
plate and figure. (Type loc. "Paraguay"). It is unlikely that the specimens 
so called by Lea came from Paraguay; they look very much like the form he 
described as peculiaris (which is a hybrid): delodontus x Uruguay ensis . Mar- 
tens' (1895: 34) "Unio paraguay anus" is probably the same. 

Diplodon firmus , Simpson, 1900: 874 ("more solid than peculiaris"); 1914: 1233 
("allied to ' 'paraguay ensis'"). Bonetto, 1966: 40 (under rhuacoicus). 

Diplodon charruanus in part, by authors, not Unio charruana d'Orbigny 1835. 
Haas, 1930: 190. Barattini, 1951: 239. Castellanos, I960: 88. 

Diplodon rhuacoicus in part, by authors, not Unio rhuacoica d'Orbigny 1835. 
Bonetto, 1964: 325; 1965: 40. 

Diplodon delodontus, Simpson, 1900: 873. Haas, 1930: 182, 190 (in part). Ba- 
rattini, 1951: 240. Bonetto, 1954: 40; 1959: 47; 1965: 43. Bonetto, Pignalberi 
& Maciel, 1962: 170. Bonetto & Ezcurra, 1963: 17. Castellanos, 1960: 88. 
Parodiz & Bonetto, 1963: 17. Figueiras, 1965: 233. Olazarri, 1966: 24 (in 
part). Parodiz, 1968: 410. Mansur, 1970: 60. Parodiz, 1971: 34 (Amer, 
malacol. Union, ann. Reps.). 

In the synonymy of Diplodon delodontus were included also (by Haas 1930 and sub- 
sequent authors) several names which do not belong there: Unio ampullaceus Lea 1866 
and D. podagrosus Marshall 1923, both equal to D. uruguayensis; U. fokkesi Dunker 
1853, a hybrid form between D. uruguayensis and D. expansus; U. browni Lea 1856, a 
synonym of D. rhombeus Wagner 1827; also, D. smithi Marshall 1917, under D. delo- 
dontus by Bonetto (1954, 1965), is equal to D. burroughianus . 



250 



PROC. FOURTH EUROP. MALAC. CONGR. 





FIGS. 1-5. Umbonal views of left valves of Diplodon. FIG. 1. Diplodon delodontus delodontus 
(Lam. ). FIG. 2. Diplodon solisianus (d'Orbigny). FIG. 3. Diplodon delodontus wymani (Lea). 
FIG. 4. Diplodon uruguayensis (Lea). FIG. 5. Diplodon expansus (Küster). 



Comparing descriptions and illustrations, I agree with Haas (1930) and Bonetto 
(1955, 1965) to include Unto paraguayensis Lea 1866 in the synonymy of Diplodon 
delodontus delodontus. However, collections from the region between Sao Paulo and 
the Paraguay River (a gap of about 500 miles, from where intermediate forms of this 
group are scarcely known) are needed to establish the status of D. paraguayensis; the 
only sample of this form, mentioned by Haas as delodontus, is a single valve from 
Concepción, Paraguay. 

Complete description . Shell elliptical, anterior margin normally rounded from the 
end of the very short lunule to the ventral margin, which is straight in the larger 
specimens and somewhat curved in the smaller ones. Dorsal margin descending 
obliquely, or in a slight curve, from the umbos to the posterior margin, which begins 
approximately at the middle of the dorsal wing; the connection of these 2 margins 
form an obtuse angle. The posterior margin meets the ventral one at a point below 
the lower half of the shell; here again a slight angle may be formed, or both posterior 
and ventral margins fuse into a continuous curve. These angles are variable according 
to the individuals, the longer ones being more elliptical, the shorter ones more rhom- 
boidal. The dorsal slope below the wing is rounded, but sometimes a weak carina is 
insinuated. The valves are inflated from the umbo to the middle of the shell, and from 
that point become rapidly compressed toward the center of the ventral margin, where 
some radial rugosities appear; the major inflation is posterior to the umbo, a little 
below the slope. The umbos are prominent in relation to the anterior end, but low in 
comparison with the ligamental area; the umbonal disk, however, is rather outstanding 
on account of the lateral inflation. The umbonal sculpture consists of 13, occasionally 
15, ribs regularly distributed but extending below the line of the beginning of the 
anterior margin (that is, no lower than the lunule). There is also a microsculpture 



PARODIZ 



251 






FIGS. 6, 7. Diplodon delodontus (Lam.). Paraná" River near Santa Fe, Argentina. FIG. 8. 
Diplodon delodontus. Gerontic specimens from Lujan River at Pilar, Argentina (MACN 11570). 
All 1/2 size. 



252 PROC. FOURTH EUROP. MALAC. CONGR. 

of concentric lines between the ribs, and sometimes for each 4 or 5 of these costil- 
lar lines there is one stronger one which crosses the ribs, forming minute nodules 
(but this is not a reliable diagnostic feature). There are 3 or 4 of these concentric 
costulae per mm. Three of the main ribs radiating from the tip of the umbo are 
coalescent; the 2 on the side meet a short distance from the tip forming a V, and the 
central one unites with them at the angle. In all cases such sculpture is not as strong 
and not so conspicuous as in Diplodon solisianus. The rest of the shell is very rugose, 
with coarse concentric folds of growth and some radiating lines centrally which are 
strictly cuticular. The color of the periostracum is very clear brown at the centre 
of the shell, but it becomes very dark toward the margins, principally on the posterior 
slope in a mixture of dark green with dark chestnut. The ligament is rather narrow, 
with its insertion a little posterior to the middle of the lateral teeth, not deep. The 
narrow lunule is not always well marked. The interior of the shell is pure white (for 
which Lea called it U. lacteolus) and iridescent toward the anterior and posterior 
margins. 

Hinge: Left valve with pseudocardinals divided into 2 conic pieces, the anterior one 
larger with sharp crenulated edge, and the posterior one an acutely pointed tooth; 
between them there is a deep fossa divided by an internal bar, and the entire surface 
of this fossa is rugosely striated. At the base of the anterior denticle there is a deep 
circular cavity corresponding to the anterior retractor, separated from the anterior 
adductor by the wall of the tooth base which falls, perpendicularly, to the adductor 
scar, which is semicircular and confluent to the elongated inferior scar. There are 2 
parallel, arcuate, lateral teeth, of which the lower one is wider, ending at the posterior 
adductor, which is very shallow. 

The right valve has its pseudocardinal bifurcated in a longitudinal oblique direction, 
the lower part of it forming a thick, large and rugose tooth; the upper part is just a 
narrow bar. 

The umbonal cavity has 4 or 5 irregular and rather large mantle muscle scars. A 
short but relatively wide interdentum is noticeable. A line, visible inside the valves 
and running from the umbo to the adductor, corresponds to the external dorsal ridge. 
The depressed exterior middle area of the anterior portion shows inside as a thickening. 
The palliai line is well impressed. 

Type locality . In Lamarck's description the habitat was unknown. D'Orbigny 
collected the species at several localities on the Uruguay and La Plata Rivers. The 
synonyms U. lacteolus Lea and U. rudus Lea were described from the La Plata River; 
U. divaricatus and U. firmus Lea were described from the Uruguay River. The 
species is more abundant in the southern half of the Uruguay River and the lower course 
of the Paraná. The locality Brazil (Rio Grande do Sul) mentioned by Mansur (1970) 
was taken from Martens, Simpson and other authors, but apparently no actual speci- 
mens were examined. 

Distribution. Rio Batel, west of Goya, Corrientes, Argentina (d'Orbigny). Paraguay 
River at Concepción (Haas)! Haas also indicated "North of Patagonia," probably 
from a specimen with a wrong label. 

Materials observed at the Carnegie Museum . Laguna Guadalupe, Santa Fe, Argen- 
tina; Arroyo Urquiza S. of Colón, Entre Rios, Argentina; Arroyo Guaviyú, S. of Salto, 
Uruguay; Arroyo Malo, Paysandú and Arroyo Miguelete, Colonia, Uruguay. In the 
Museo Argentino de Ciencias Naturales, Buenos Aires, gerontic specimens from the 
Lujan River, prov. of Buenos Aires (Fig. 8). 

Dimensions . Fifty specimens were measured from the lot of Arroyo Guaviyú: 
length 64.2-84.5, mean 72.6 mm; height 35.4-52.9, mean 46 mm; width 24.1-36.3, 
mean 30.8 mm; distance from umbo to anterior margin 12.1-23.9, mean 17.5 mm. The 
largest specimen observed was from Laguna Guadalupe: length 95, height 60, distance 



PARODIZ 253 

from umbo to anterior margin 25 mm; it represents a typical, oversized Diplodon 
delodontus. 

Individual variations. The most variable external features of Diplodon delodontus 
are shell length and the angulosity of the posterior margin; in some specimens the 
margin is almost rounded (as in what Lea called U. rudus), but in the majority the 
degree of angulosity differs. The color varies less, and a few shells in a population 
may be olive-green, especially in the area around the umbo. The hinge varies more 
according to age, the older hinges obviously stronger, but in individuals not especially 
old, but short, it is also strong. Sometimes the larger piece of the pseudocardinal 
of left valve has a longitudinal sulcus, giving the impression of a trifid tooth, but such 
a feature is not frequent. 

The most constant feature in this species is its general shape, within the limits of 
moderate variations, and the peculiar very rugose surface of concentric furrows, 
thickened at the lines of growth. Also, the anterior and ventral margins show an 
imbricate aspect, with stronger rugosities on the posterior margins. 

Evidently, the above description and observations of the typical Diplodon delodontus 
correspond to what have been clearly described by Lea as U. lacteolus and U. rudus. 
Unio fokkesi Dunker, which most authors synonymized under delodontus, might be 
that species, but the type in the Senckenberg Museum, figured by Haas, has a different 
shape and it is with all probability a hybrid of other east-northern forms. Unio 
divaricatus Lea, erroneously described as from Egypt, is a Diplodon delodontus (but 
not of typical form); Drayton's figure of the umbonal sculpture (pi. 9, fig. 5) is 
exaggerated. 

Hybrids . In comparison with other species of the complex, Diplodon delodontus 
offers less numbers of individual hybrids in its populations, and yet, the types of such 
hybrids show a greater mixing. From the Paraná to the Uruguay River across Entre 
Rios, and down to La Plata River at Colonia, the populations of D. delodontus are 
relatively uniform, agreeing with the typical pattern. In the southern localities, 
however, specimens are smaller but still typical and distinguishable from the sub- 
species D. delodontus wymani. The 2 subspecies have been easily identified by most 
authors; when intermediates are found there is no doubt that these are hybrids. At 
Arroyo Malabrigo, Santa Fe, populations of D. delodontus delodontus hybridize with 
D. solisianus, this last species being dominant; the umbos, sculpture and posterior 
slope of the hybrids are like those in D. solisianus, but the rugose surface and thick- 
ness is as in D. delodontus, although more compressed. In no way is it possible to 
consider such forms as clinal, because there is no gradual modification of characters 
through a large area; the individual hybrids occur only in the zone of overlap of both 
species. Although they may reappear in other places in their typical forms, there is 
always one species dominant over the other, and D. delodontus recedes where D. 
solisianus is abundant, and vice versa. 

Mature glochidia in Diplodon delodontus delodontus are found from April to November. 
The glochidia, according to Bonetto, are of large size (although not so large as those 
of D. paulista), of about l/3 mm, and present scarce variability. The marsupium 
occupies the entire free gill. 

Diplodon delodontus wymani* (Lea 1860); Figs. 3, 9-11 

Unio Wymanii Lea, I860: 90; 1863a: 17, 25, pi. 42, fig. 289; 1863b: 381 (same 
pi. and fig. ); 1867: 23. Sowerby, in Reeve, No. 449. Martens, 1868:193. 
Doering, 1875: 45 (wymani). 

Margaron {Unio) Wymanii Lea, 1870: 35, 103, 137. 

Unio delodonta, Hie ring, 1893: 117. 

Diplodon wymanii, Simpson, 1900: 874; 1914: 1230 (Simpson noted: "extremely 



254 PROC. FOURTH EUROP. MALAC. CONGR. 

close to apprimus", which is D. Uruguay ensis). Haas, 1916:12, 47. Caste- 
llanos, 1965: 104. 
Diplodon felipponei Marshall, 1917: 381, pi. 50, figs. 1-3, pi. 51, fig. 1. Ort- 

mann, 1921: 520 (as lacteolus) = d. wymani x d. delodontus. 
Diplodon ladeólas, Ortmann, 1921: 518, 519 (in part). 
Diplodon (Cyclomya) paranensis funebralis, Haas, 1931:36 (in part, not fune- 

bralis Lea 1860; from Arroyo del Gato, La Plata). 
Diplodon delodontus wy manii, Haas, 1930: 192 (in part). Bonetto, 1954: 41; 1964: 

325. Bonetto & Ezcurra, 1962: 35. Castellanos, I960: 89, pi. 2, fig. 13. 

Figueiras, 1965: 233. Olazarri, 1966: 18, 21, 24 (in part). 
Diplodon delodontus wymani, Barattini, 1951: 240. Parodiz, 1968: 5, 11, 16. 

Mansur, 1970: 62. 

*Spelling corrected according to Art. 32 ii, Appendix D II of the International 
Commission on Zoological Nomenclature. 

Although the type locality was given as Uruguay River, Diplodon delodontus wymani 
inhabits only the lower portion of that river and the same portion in the Paraná, being 
more characteristic of the Paraná Delta, La Plata River and its affluents in the Buenos 
Aires province. Many references to "Uruguay" are due to its having been confused 
with D. uruguayensis . Thus, it can be differentiated easily geographically as a sub- 
species from D. delodontus delodontus, which may be found overlapping with it in the 
marginal areas. 

Lea's description suffices to identify the subspecies without difficulty, in spite of 
certain undefined expressions (the adverb "somewhat" was used 4 times). A charac- 
teristic not mentioned by Lea, but which shows well in its figure, is the thinness of 
the periostracum, dehiscent principally at the margins; the periostracum is also more 
brilliant than in Diplodon delodontus delodontus. Sowerby's (in Reeve) fig. 449 was 
indicated as taken from one of Lea's specimens, but the greenish coloration is exag- 
gerated. 

Of all the forms in the Diplodon delodontus complex, D. delodontus wymani has the 
flattest valves, and its contour forms an almost perfect arch with slopes equally 
descending on both sides, and its umbo is placed in a more anterior position than that 
in any of the others. The figure of D. felipponei in Marshall (1917) represents the 
typical form of D. delodontus wymani. The lateral teeth in D. delodontus wymani are 
thinner and sharper than in D. delodontus delodontus and, compared with D. uruguay- 
ensis, there is practically no interdentum. 

Apparently Diplodon delodontus wymani is not an abundant but a rather scarce 
subspecies, and its records in collections are few (when those of D. uruguayensis 
labelled as D. d. wymani are eliminated). In the marginal areas where D. delodontus 
delodontus and D. delodontus wymani overlap, the typical delodontus form is always 
more abundant, so that when crossbreeding occurs, it shows predominantly in the 
progeny, and since the parents are conspecific, there is more probability of the 
fertility diminishing the genetic gap than in other hybrids. That might account also 
for the proportional scarcity of D. delodontus wymani. Therefore only hesitantly 
can the crossbreeding be termed true hybridization, a designation more fitting when the 
condition is produced by 2 properly differentiated species. 

Haas (1930) united Diplodon apprimus (Lea) with D. delodontus wymani, but the 
former name corresponds to an oversized D. uruguayensis. As for D. felipponei 
Marshall, its author recalled that it "mimics" D. delodontus wymani (it is not D. 
paranensis or D. funebralis as referred by other authors); it is, as its type (in the 
U.S. National Museum) figured by Marshall shows, one of the hybrids, with a shape 
agreeing with that of D. delodontus wymani, but with surface and inflation closer to 



PARODIZ 



255 





10 



11 



FIGS. 9-11. Type of Diplodon felipponei Marshall = typical Diplodon delodontus wymani (Lea). 
1/2 size. 



256 PROC. FOURTH EUROP. MALAC. CONGR. 

D. delodontus delodontus, for which Ortmann included it in "D. lacteolus." 

Materials at Carnegie Museum. Typical specimens are from Arroyo Los Gatos, 

North of city of La Plata, Buenos Aires province. From Arroyo Las Tunas (affluent 

of Tigre River, Paraná) there is a hybrid with D. delodontus delodontus. There are 

many specimens from Paraná River at Sta. Fe. 

The majority of the typical populations examined at the Museo Argentino de Ciencias 

Naturales at Buenos Aires are from the Paraná Delta and southwest (Figs. 12, 13); also 

hybrids (Fig. 16). 

The specimen observed by Ortmann from a "pond along the Negro River, Uruguay" 

(collected in 1912 by J. Haseman) and referred as Diplodon uruguayensis, is a young 

of Diplodon delodontus wymani, extra -limitai. 

Diplodon uruguayensis (Lea 1860); Figs. 4, 14, 15 

Unio uruguayensis Lea, I860: 90; 1863: 388, pi. 45, fig. 298; 1863a: 241, pi. 
45, fig. 298. Sowerby, in Reeve, 1868: pi. 84, fig. 448 ("Uruguay Riv. "). 
Doering, 1875: 45. Paetel, 1890: 171. 

Unio piger Lea, 1860: 90; 1863: 23, pi. 45, fig. 296. Sowerby, in Reeve, 1868: 
pi. 84, fig. 445. Doering, 1875: 45. Martens, 1868: 212. (Under D. delo- 
dontus wymani by Haas, 1931 and Castellanos, 1960; under charruanus by 
Bonetto, 1964). 

Unio apprimus Lea, 1866: 34; 1868: 263, pi. 33, fig. 78; 1869: 23, pi. 33, fig. 
78. Simpson 1900: 874. (Under D. wymani by Simpson, 1914, by Haas, 1931 
and by Castellanos, 1960; under D. uruguayensis by Ortmann 1922). 

Unio ampullae eus Lea, 1866: 34; 1868: 269, pi. 35, fig. 83 (type locality "South 
America" -Paz); 1869: 29, pi. 35, fig. 83. (Under/), delodontus by Haas, 
1931; under D. charruanus by Castellanos, 1970). 

Unio peculiaris Lea, 1866: 33; 1868: 265, pi. 34, fig. 80; 1869: 25, pi. 34, fig. 
80. 

Unio caipira Diering, 1893: 98, pi. 4, fig. 9i, h ("Southern Brazil"). Nehring, 
1894: 83. Bonetto; 1965: 44 (under D. delodontus expansus). = D. uruguay- 
ensis x D. expansus. 

Margaron (Unio) uruguayensis Lea, 1870: 46, 103, 136. 

Margaron (Unio) apprimus Lea, 1870: 46, 102, 111. 

Margaron (Unio) ampullaceus Lea, 1870: 53, 102, 110. 

Margaron (Unio) piger Lea, 1870: 46, 102, 128. 

Margaron (Unio) peculiaris Lea, 1870: 47. 

Diplodon apprimus, Simpson, 1900: 874; 1914: 1231. Haas, 1916: 12 (under/). 
delodontus wymani). 

Diplodon ampullaceus, Simpson, 1900: 874; 1914: 1230. Haas, 1916: 11. Ort- 
mann, 1921: 518 as D. burroughianus? 

Diplodon piger, Simpson, 1900: 875; 1914; 1236. Bonetto, 1965: 50 under D. 
charruanus . 

Diplodon delodontus (in part), Barattini, 1951: 240. 

Diplodon delodontus wymani (in part), Barattini, 1951: 240. Castellanos, I960: 
89. Bonetto, 1965: 43, 50. Figueiras, 1965: 234. Olazarri, 1966; 24. 

Diplodon charruanus (in part), Bonetto, 1964: 327; 1965: 50. Figueiras, 1965: 
238. Castellanos, I960: 88. Bonetto & Ezcurra, 1962: 31, 39. Olazarri, 
1966: 26. 

Diplodon uruguayensis, Simpson, 1900: 875; 1914: 1234. Ortmann, 1921: 512, 
547. Parodiz, 1968: 3, 9, 11. Mansur, 1970: 65, 66. 

The original description agrees entirely with the specimens identified by Ortmann 
in 1921 as Diplodon uruguayensis from the Rio Negro in Uruguay. This is a solid 
species, thick, inflated, with umbos rather flat and the hinge strong, easily distin- 
guishable from D. delodontus wymani. 



PARODIZ 



257 






FIGS. 12-13. Diplodon solisianus (d'Orbigny). Aged specimens from La Plata River (MACN 
10662) in which the axial costulae have been smoothed. 



258 PROC. FOURTH EUROP. MALAC. CONGR. 

Distribution . Common in the Uruguay River and tributaries, but found also in 
rivers of southern Brazil up to the Tietê, where it hybridizes with Diplodon expansus 
(Ihering named the latter populations Unio caipira, of which a paratype is at the Carne- 
gie Museum; it is not related to D. ellipticus as Simpson thought.) U. apprimus Lea is 
an extreme clinal stage, of large size, in the western distribution of the species, and 
it cannot be associated with D. delodontus wymani as several authors have indicated, 
but, as Ortmann considered it, belongs to D. uruguayensis . 

Materials at the Carnegie Museum . Uruguay: Rio Uruguay, Rio Negro, Rio Queguay, 
and Arroyo Artilleros near Colonia. Argentina: Arroyo La Leche, Colón, Entre Rios. 
Brazil: Camaquam, Guahyba, Jacuhy and Cachoeira rivers in Rio Grande do Sul; also 
Rio Tietê, Sâo Paulo (D. caipira = D. uruguayensis x D. expansus). 

Unio fokkesi Dunker 1853 and Diplodon trivialis Marshall are also hybrids with D. 
expansus, as indicated by Mansur (1970), both from Southern Brazil (the locality "Rio 
de la Plata" given by Dunker to U. fokkesi is not correct). 

In the Senckenberg Museum there are specimens received from Ihering (No. 11301) 
which are Diplodon uruguayensis x D. delodontus from the Camaquam River; also there 
are several lots of D. uruguayensis labelled by Ihering as U. lacteolus, U. apprimus 
and U. wymani, and by Bonetto as D. charruanus. 

Typical specimens in Figs. 14, 15 are from the Uruguay River at Paysandú (MACN 
15307). 

The character of the hinge, as Ortmann indicated, changes with age, the pseudo- 
cardinals becoming more stumpy. 

In coloration, Diplodon uruguayensis resembles D. piceus, but the size is greater, 
more inflated, thicker, with stronger hinge and very wide and thick prismatic area 
(this last character is conspicuous, even in populations of D. uruguayensis x D. 
delodontus). A clinal variation resulting in heavier shells occurs in southern Brazil, 
inhabiting rapid streams and having umbos much eroded, but in those better preserved 
the umbonal ribs appear stronger than in D. piceus. 

Ortmann separated Diplodon uruguayensis and D. piceus (he called the latter D. 
charruanus) collected simultaneously at the same place (Ponds of Santa Isabel, Rio 
Negro, Uruguay) by J. Haseman in 1909. Also the glochidia which Ortmann mentioned 
from these specimens as D. charruanus (and by Bonetto, 1961: 24) actually belong to 
D. piceus. Under D. piceus, Ortmann (1921: 506) included a number of different 
species: D. charruanus, D. rhuacoicus and D. aethiops. On the other hand, the glochi- 
dia studied by Bonetto from specimens in the Museu Paulista (and labelled by Ihering 
as U. aethiops Lea) from the Camaquam River are D. parallelipipedon aethiops (Lea); 
corresponding specimens of the same lot distributed by Ihering are at the Carnegie 
Museum (see Parodiz, 1968: 12). From these considerations and the corrected identi- 
fications, the glochidia of D. piceus {-D. charruanus after Ortmann, not d'Orbigny) 
must be of direct development in the subgenus Rhipidodonta, unrelated to D. uruguay- 
ensis and unlikely would hybridize with it. 

Dimensions (mean in mm): Length Height Width No. specimens 



Southern Brazil 












Camaquam River 


(1) 


72 


46.5 


30 


3 


Camaquam River (2) 


70.5 


41 


28.5 


13 


Camaquam River 


(3) 


73 


47 


30 


1 


Guaiba River 




71 


47 


39 


1 


Uruguay 
Rio Negro 




75 


45 


35 


6 


Santa Ana 




62 


37 


28 


19 


Uruguay River 




69 


41 


31 


1 


San José' 












uruguayensis x delodontus 


63 


38.5 


28 


7 



Mean of 51 specimens 70. 7 47 32. 7 



PARODIZ 



259 





. . -'*" 




FIGS. 14-15. Diplodon uruguayensis (Lea). Uruguay River, near Paysandvi, Uruguay (MACN 
15307). FIG. 16. Hybrid Diplodon solisianus x wymani. Rio de la Plata. 



260 PROC. FOURTH EUROP. MALAC. CONGR. 

Diplodon solisianus (d'Orbigny 1835); Figs. 2, 12, 13, 16-18 (hybrids) 

Unio solisiana d'Orbigny, 1835: 34, No. 12; 1842: 604, pi. 69, figs. 1-3. Sow- 
erby, in Reeve, 1868: No. 508, pi. 93 (fig. from d'Orbigny's specimens in 
British Museum). F. Corsi, 1900: 449 (fig. 32 under soliciana is Diplodon 
paranensis funebralis (Lea)). Doering, 1876: 6. 

Diplodon solisianus, Simpson, 1900: 887; 1914: 1287. 

Diplodon (Bulloideus) solisianus, Haas, 1931: 38. Castellanos, I960: 27, pi. 5, 
figs. 4, 8. 

Diplodon (fihipidodonta) variabilis, Bonetto, 1965: 47. Figueiras, 1965: 236, 
237. Olazarri, 1966: 25 (solisiana). 

Diplodon solisianus, Parodiz, 1968: 10, 16, 20. 

Complementary description . Shell oval, but less elliptical and more rounded than 
in Diplodon delodontus; anterior -dorsal margin with small but well formed lunule, 
after which it descends in a continuous rounded line with the anterior margin; from 
the middle of the anterior margin the line descends rapidly and obliquely toward the 
ventral margin, which curves upward; the union of the ventral and posterior margins 
forms a rounded angle a little below the middle of the shell; from there the posterior 
margin is rather straight affected only by a slight undulation at the point where the 
posterior ridge ends. The dorsal margin is almost straight along the ligamental 
section and then descends obliquely to meet the posterior margin; the posterior ridge 
is well marked with a (sometimes double) carination, above which the wing is higher 
and thinner than in D. delodontus; viewed from the top the posterior dorsal margin 
shows an escutcheon; sometimes also the wing has very faint flutings. The umbos 
are larger, more prominent and higher than in D. delodontus, with stronger radial 
sculpture, further apart and more inclined to project into rugosities over the rest 
of the shell; the 2 central bars form a large V, in contrast with the short V of D. 
delodontus; although the number of bars is equal in both species, in D. solisianus 
they are stronger near the beginning of the posterior ridge; the microscopic concentric 
striae on the umbo are very profuse. The concentrically striated lines of growth are 
not as coarse as in D. delodontus. The color at the center and upper part of the shell 
is olive-green, paler in juvenile specimens, but around the margins and posterior 
wing the color is dark brown; sometimes there are alternating bands of the 2 colors. 
The periostracum near the umbo peels easily. The greater inflation of the valves, 
instead of being back and posterior to the umbo as in D. delodontus, is more to the 
center and the compression toward the margins is more noticeable; the mark of the 
ligament insertion above the lateral tooth is similar, but shorter. The cavity under 
the umbo is deep. Hinge: left valve with pseudocardinal bifid or trifid (usually appearing 
as having 2 teeth, but they are united by a superior ridge), the posterior division 
directly under the umbo, stronger, but these characteristics are variable; the laterals 
have a sinuous line, curved upward at the middle and then descending, and ordinarily 
more separated from the pseudocardinals than in£>. delodontus, thus forming a perfect 
interdentum. On the right valve the pseudocardinals are, in general, stronger. The 
anterior adductor scars are smaller but deeper than in D. delodontus; the palliai line, 
as well as the posterior adductor, is less marked. 

Type locality . D'Orbigny indicated several localities in the vicinity of the La Plata 
River and Maldonado. The name solisianus refers to the Solis River of Uruguay, which 
empties at Maldonado (derived from Juan de Solis, discoverer of La Plata River in 
1515). Maldonado should be selected as the type locality, although today the species 
seems to be less common there than on the west side. 

Materials observed. Province of Santa Fe: Arroyo Malabrigo, near Roman (where 
it lives sympatrically with D. delodontus), Carnegie Museum; Province of Buenos 
Aires: Arroyo Los Cuervos, Ramallo; Arroyo Los Pozos, 50 km SW of Buenos Aires 



PARODIZ 



261 








FIGS. 17-18. Hybrid Diplodon solisianus x delodontus. Paraná River at Santa Fe, Argentina. 
FIGS. 19-21. Diplodon expansus (Küster). Ibicuy del Norte Island, Parana* River, Paraguay 
(MACN). 



262 PROC. FOURTH EUROP. MALAC. CONGR. 

city, both in the Carnegie Museum; Rio de la Plata, Museo Argentino de Ciencias 
Naturales. Castellanos (1960) reported the species from several small streams in the 
vicinity of La Plata. 

Diplodon solisianus can be easily distinguished from D. delodontus. Its anterior 
dorsal half is somewhat similar (more oblique in D. solisianus), but its posterior 
half is decidedly subquadrate; its shape is always higher and shorter, more compressed, 
with more prominent umbos and radial sculpture stronger. In some more angulated 
individuals of D. delodontus, the angle is at the posterior side of the base, while D. 
solisianus is more rounded at the point, and the angle appears higher near the middle 
line; also the posterior dorsal margin forms in D. solisianus an almost right angle 
at the wing. 

Individual variations. Young specimens are sometimes more elongated, with radial 
ribs and the posterior ridge more marked; they turn more inflated with age. 

Diplodon solisianus seems to be less common than its allied species in large rivers, 
and it usually appears in small creeks. From "lagunas" of northern Santa Fe where 
D. solisanus co-habits with D. delodontus, hybridization can be detected in more 
elongated specimens which grow thicker, but the populations are largely distinct and, 
although sympatric, where the populations of D. delodontus increase, those of D. 
solisianus decrease; hybrids have been observed when the 2 populations are in the 
same proportion. In the south (Arroyo Los Pozos) a lot consisting of 3 specimens 
shows 2 of them closer to the typical D. solisianus, and the 3rd is shaped like D. 
delodontus wymani. Specimens like these are usually labelled simply as wymani or 
delodontus in collections. This species has also been mistaken for D. paranensis, 
D. paranensis funebralis or D. fontaineanus ; but apart from their embryological dif- 
ferences (D. solisianus has parasitic glochidia, while the D. paranensis group has 
direct development), D. paranensis is very circular in shape and its only angulosity 
is at the posterior wing, with very shallow adductors and umbos considerably smaller; 
D. paranensis funebralis is very flat, with an umbo so advanced that there is practi- 
cally no anterior dorsal margin, and the line of the anterior margin is almost vertical. 

Distribution. The range of Diplodon solisianus is along the southern part of the 
Paraná River and tributaries of the Plata. Apparently it is absent in the Uruguay 
River drainage. It probably covered a larger area in pre-Pleistocene times before 
the formation of La Plata drainage. The last Pleistocene ingression, Querandinan, 
separated the populations at both sides of the present La Plata estuary. Although 
D. solisanus and D. delodontus overlap greatly in their areas of the Paraná, D. solisi- 
anus does not appear in the province of Entre Rios as D. delodontus does; more col- 
lecting in that area, however, may prove the extension of its range. 

Sowerby (in Reeve) figured a specimen of Diplodon solisianus from d'Orbigny's 
materials in the British Museum (the collection of that museum contains the holotype, 
and 11 paratypes, but the localities of Buenos Aires and Maldonado have been mixed). 
That illustration differs from the figure by d'Orbigny, but agrees completely with our 
observed specimens from Arroyo Malabrigo, except for the reference by Sowerby 
(followed by other authors) to the divergent umbonal ribs, for which an acclaration is 
in order: d'Orbigny only indicated 10-12 ribs, without mention of divergence; it was 
Sowerby who added "a few slantingly divergent subradiating ribs which in the suborbi- 
cular form delineated by d'Orbigny extend over the entire surface." Such reference 
indicates only that the ribs radiate and diverge from the beak; subsequent coalescence 
of central ribs were not considered in the original description of many species. It must 
be also noted that illustrations in d'Orbigny's work, especially those by Annedouche, 
were not always very accurate, especially in regard to hinge characters and colors. 
Sowerby' s figure is closer to the actual specimens, even if the sinuosity of the ventral 
margin is somewhat exaggerated. 



PARODIZ 263 

Diplodon subquadratus Marshall has been indicated (Castellanos, 1960) as belonging 
to D. solisianus; the specimens illustrated by Castellanos as such are truly D. 
solisianus, but D. subquadratus is more inflated posteriorly, with weaker hinge line, 
wider prismatic area, and its type locality is Paysandú, Uruguay, from where many 
collections have been made without D. solisianus being yet found. D. subquadratus 
belongs to the group (and it is probably a synonym of) D. variabilis (Maton). 

Dimensions (means of lots): Length Height Width 

Arroyo Malabrigo, Santa Fe, 

21 specimens 62. 8 46. 5 23. 7 

"Lagunas" near Arroyo 

Malabrigo, 5 specimens 81 60. 5 33 

Arroyo Los Pozos , Buenos 

Aires, 3 specimens 82 63 32 

Small specimen from Arroyo 

Los Cuervos , Buenos Aires 50 41 20. 5 

Mean of Total 68. 9 52. 7 27. 3 

These figures show that, in comparison with Diplodon delodontus, D. solisianus is 
shorter, higher and more compressed. 

One specimen in the Seckenberg Museum (No. 3859) from La Plata River and 
labelled "paratype" (!) of Diplodon s olis ianus - ex-Copenhagen Museum from Ihering' s 
collection) - is but a very young and thin individual of D. variabilis (Maton), inflated 
and with a different hinge. Haas, however, identified the true D. solisianus (No. 11431) 
from La Plata River. 

Hybrids of D. solisianus x D. delodontus from the Paraná River at Santa Fe are 
shown in Figs. 17, 18. 

Diplodon martensi (Ihering 1893) 

Unio martensi Ihering, 1893: 100, pi. 4, fig. 10. 

Unio firmus boettgeri, Ihering, 1893: 105, pi. 4, fig. 2 (as "granosus multistri- 

atus", Haas, 1930: 32 and Bonetto, 1965: 37). 
Unio sebastiani Ihering, in litt, (label Senckenberg Museum), nomen nudum. 
Diplodon binneyi Simpson, 1900: 878 (as Diplodon, from Lea's Unio binneyi, 

1845: 165, "southern U.S.A.".); see acclaration by Parodiz, 1968: 2. 
Diplodon suppositus Simpson, 1914: 1245 (named, but undescribed, by Ihering, 

1893). (As D. rhuacoicus by Haas, 1930). Marshall, 1917: 385, pi. 51; 

Bonetto, 1961: 33. Zanardini, 1965: 6, 9. Figueiras, 1965; 238. Morretes, 

1949: 19. 
Diplodon santa-mariae Simpson, 1914: 1270. Ortmann, 1921: 495. Marshall, 

1917: 386, pi. 52, fig. 6, pi. 55, figs. 1-4. Morretes, 1949: 20. Haas, 1930: 180 

(under D. rhuacoicus). Bonetto, 1965: 39 (under D. granosus multistriatus) . 
Diplodon decipiens Ortmann, 1921: 499, pi. 36, figs. 3, 6, pi. 45, fig. 4, pi. 48, 

fig. 7. Haas, 1930: 180 (under D. rhuacoicus). Bonetto, 1964: 325 and 1965: 

44 (under D. delodontus expansus). 
Diplodon imitator Ortmann, 1921: 469, 491-500, pi. 34, figs. 5, 7. Bonetto, 

1961: 16. Figueiras, 1965: 235 (in part). 
Diplodon simillimus Ortmann, 1921: 495-500, pi. 35, figs. 3, 6, pi. 45, fig. 2. 

Haas, 1930: 180 (under D. rhuacoicus). Bonetto, 1961: 11. 
Diplodon vicarius Ortmann, 1921: 496, pi. 35, figs. 7, 8, pi. 36, figs. 1, 2. Haas, 

1930: 180 (under rhuacoicus). Bonetto, 1961: 10; 1965: 39 (under D. granosus 

multistriatus). 
Diplodon rhuacoicus, Haas, 1930: 180. Castellanos, 1960: 68 (in part). Bonetto, 

1961: 18 (under D. piceus); 1965: 40. Figueiras, 1965: 225. Parodiz, 1968: 



264 PROC. FOURTH EUROP. MALAC. CONGR. 

9, 15. Mansur, 1970: 77. (The last 2 references under D. rhuacoicus proper, 

not in part. ) 
Diplodon granosus multistriatus, Haas, 1931: 32. Bonetto, 1964; 324 and 1965: 

39. 
Diplodon delodontus expansus, Bonetto, 1964: 325 (in part). 
Diplodon charruanus, Olazarri, 1966: 26 (in part). 
Diplodon martensi, Simpson, 1900: 882; 1914: 1266. Haas, 1930: 180 (under D. 

rhuacoicus). Parodiz, 1968: 7, 14, 15. Mansur, 1970: 74. 

Simpson, in a transcription of the description (1914), said that the shell of this 
species is rhomboid, little wider behind, with posterior ridge low and base line a 
little curved at the middle. I have observed the last character in paratypes of the 
nominal species D. simillimus and D. decipiens, which occurs on specimens living 
in fast running waters and stony substratum. 

Type locality . The only clearly stated location given by Ihering was Taquara in the 
Vacahy river drainage, Rio Grande do Sul; Haas (under Diplodon rhuacoicus) referred 
also the "type" of D. martensi as Rio Grande do Sul, not Sâo Paulo, which Ihering 
referred with the mark "?". 

The intricate synonymy of Diplodon martensi includes several names given by 
Ortmann and Simpson as presumable new species, which are only parts of clinal 
variations. More complicated is its assumed relationship with D. rhuacoicus, under 
which (in part) it was placed by Haas and Bonetto (the confusion originated in Sowerby's 
figure of D. charruanus as D. rhuacoicus, and under that name, afterwards D. mar- 
tensi, as well as D. piceus, and even D. parallelipipedon aethiops, were wrongly 
subordinated). 

The shape of Diplodon martensi is very elongated-oval with the anterior and poste- 
rior margins well rounded, except for a slight angulosity at the posterior end. Diplo- 
don rhuacoicus is more inflated and solid, narrower and well angulated behind, and 
the umbos are more prominent. The hinge teeth in D. martensi are reduced (in com- 
parison with D. rhuacoicus) and are of the same type found in D. decipiens, D. vicarius, 
etc.: the left valve has a small pseudocardinal tooth with rugosities under and behind 
it, but such a character is variable and the teeth may grow stronger as in D. simillimus; 
in D. rhuacoicus the pseudocardinal in the left valve is always large with a conspicuous 
supplementary tooth behind. 

The relationship of Diplodon martensi is closer to D. expansus and D. paulista than 
to D. rhuacoicus, in color, periostracum, flatness of valves and hinge; for all these 
characters, Bonetto placed the synonym D. decipiens under D. expansus. On the other 
hand, the synonymy given by the same author for "D. granosus multistriatus" (includ- 
ing D. vicarius, D. santamariae and D. decipiens) needs modification, because D. 
granosus (Bruguiere) from the Guianas is entirely different from D. multistriatus, 
which corresponds to D. ellipticus Wagner (Lea himself, in 1870: 31, found out that 
his Unio multistriatus was a perfect synonym of U. ellipticus); of the figures given 
by Haas (1930-1931) as D. granosus multistriatus, Abb. 24-26 agree with D. ellipticus, 
while fig. 28 is D. martensi; fig. 29, which is the type of U. pfeifferi Dunker, is an 
entirely different shell not belonging to this group. 

While Diplodon martensi seems to be a species well distributed in southern Brazil 
(Sâo Paulo, Paraná, Rio Grande do Sul), D. rhuacoicus is a very rare one, a fact al- 
ready stated by d'Orbigny in 1846. Its habitat is reduced to small streams of southern 
Uruguay (Maldonado and especially Canelones), with some eastern isolated morpho- 
logical variations (Cerro Largo), to which Marshall gave the names D. pilsbryi and 
D. yaguaronis. The larvae studied by Bonetto from northern specimens such as D. 
rhuacoicus very unlikely correspond to this species, but are more probably D. martensi; 
thus the glochidia of the real D. rhuacoicus might belong to the group of D. charruanus, 



PARODIZ 265 

i.e., may be characterized by direct development. There are populations in Canelones 
which appear to hybridize with D. charruanus, but no indications of crossbreeding 
with D. martensi or D. Uruguay ens i s have been found for D. rhuacoicus . 

The materials of Diplodon martensi observed in the Carnegie Museum correspond 
to the original lots described as D. decipiens, D. vicarius, D. sim.illim.us and D. 
imitator, and complete references can be found in Ortmann's 1921 work. Ortmann 
said that D. martensi was "impossible to identify" on account of its doubtful type 
locality. On the other hand, Ortmann declared that the 4 species he described were 
"extremely similar" and "very close" (1921: 494, 496, 499, 501). 

Diplodon expansus (Küster 1856); Figs. 5, 19-21 

Unio expansus Küster, 1856(9): 149, pi. 43, fig. 5. 

Unio effulgens Lea, 1857a: 94; 1857b: 303, pi. 28, fig. 18; 1870: 35, etc. (as 
Margaron). Simpson, 1900: 879 (as Diplodon). 

Unio eurhynchus Küster, 1861: 237, pi. 79, fig. 5 (loc. unknown). 

Unio greeffeanus Dunker {in litt.), Ihering, 1893: 96, pi. 4, fig. 8. 

Unio aethiops piracicabana Ihering, 1893: 102 (U. aethiops Lea is a subspecies 
of parallelipipedon). Simpson, 1900:874. 

Unio guahybae Ihering {in litt.: specimens so labelled were distributed by Ihering 
to many collectors). Simpson, 1900: 892 (as Diplodon). This reference is 
according to Haas and Bonetto. [Of "Unio bischoffi" and a U. sanctipauli" both 
Ihering'se'w litteris, I have no other knowledge but the indication by Haas (1930) 
that they may belong to D. expansus; they are nomina nuda]. 

Diplodon mimus Simpson, 1914: 1249. Morretes, 1949: 19. Marshall, 1917: 
383, figs. 3-6. 

Diplodon mogymirim Ortmann, 1921: 520, pi. 37, figs. 4-7, pi. 46, fig. 5, pi. 
48, fig. 2. Morretes, 1949: 19. 

Diplodon granosus multistriatus , Haas, 1931: 32. Bonetto, 1965: 39 (these re- 
ferences, in part, correspondió/), mimus). 

Diplodon delodontus expansus, Haas, 1930, 192, fig. 15. Bonetto, 1954: 41; 1964: 
325; 1965: 44. Bonetto & Drago, 1966: 122. Zanardini, 1965:8,9, fig. 1. 
Figueiras, 1965: 233. Zilch, 1967: 124. 

Diplodon expansus, Ihering, 1910: 107, 134. Simpson, 1914: 1231. Bonetto, 
I960: 48, 50; 1961: 13, 14. Parodiz, 1968: 66. Mansur, 1970: 65. 

Type locality . Conigo River at Nova Friburgo, state of Rio de Janeiro, Brazil. 

Although the species is well known from rivers of southernmost Brazil in Rio 
Grande do Sul, its greater abundance is in the Tieté River in the vicinity of Piracicaba, 
Sâo Paulo. 

Although the inclusion by most authors of Unio greeffeanus (Dunker) Ihering in the 
synonymy of Diplodon expansus (Ortmann also referred it very close to his D. mogy- 
mirim) is acceptable, the figure of this species in Ihering (1893, pi. 4, fig. 8) shows a 
peculiar radiation on the umbo, which in actual specimens (always found with eroded 
umbos) is almost impossible to detect. But the type of U. greeffeanus in the Sencken- 
berg Museum leaves no doubt of their conspecificity. Küster's description (he credited 
it to Jean Charpentier) is lean in clear-cut characters, and while he said the cardinals 
are "rather strong", the description of U. effulgens indicated "teeth small"; these are 2 
extremes in variation I found in populations of D. mogymirim, but the cardinals usually 
are strong. Simpson's observations that D. expansus (its figure is in Küster) looks 
more like an Australian rather than a South American shell is pertinent, because in 
some localities, as in the Ivai River, the shells are very thin and rough-surfaced (as 
in Hyridella australis); other Diplodon also have such peculiar aspect, as in the D. 
chilensis group; but the majority of the Tieté River materials are rather solid and 
polished, as those which Ihering called U. piracicabana, identical with D. greeffeanus - 
mogymirim. 



266 PROC. FOURTH EUROP. MALAC. CONGR. 

The materials of Diplodon expansus revised in the Carnegie Museum, includes the 
lots of types and numerous paratypes of Diplodon mogymirim (for which complete 
references and measurements are found in Ortmann, 1921), plus 1 specimen labelled 
by Ihering (from Geret Coll. of Paris) as "Unio Wymanni" (a hybrid individual of D. 
expansus x D. uruguayens is, very strong and inflated), and 3 specimens from Ivai 
River, Paraná (received from Bonetto as "D. granosus") collected by Zanardini in 
1960, which are of small size, thin and fragile. 

According to Bonetto (1961: 13), who found differences with Diplodon delodontus in 
the shape of glochidia, D. expansus would be "a well differentiated subspecies." On 
the other hand, the same author (1964: 324) considers that the elements attributable 
to D. delodontus expansus are "considerably heterogeneous" and "the situation [is] 
not clear enough." Such a statement was justified by the number of names involved in 
the synonymy. But among the "subspecies" subordinated to D. expansus, several have 
been discarded: D. enno Ortmann = D. rotundus enno; D. delodontus pilsbryi = D. 
rhuacoicus; D. fontaineanus deceptus Simpson = D. rotundus gratus (see Parodiz, 
1968: 16, 18); as for D. imitator andD. decipiens, see above under D. martensi. 

The lectotype selected for Diplodon mogymirim (for which the complete description 
by Ortmann serves also for D. expansus) corresponds to the specimen cfNo. 9, figured 
on plate 37, fig. 4a, b, c; the allotype <¡> No. 38, fig. 7a, b. These specimens were not 
measured in Ortmann' s table but are among the larger; the largest (not figured) was 
length 68, height 45, width 26 mm. Females are somewhat larger and stronger than 
males, but not always; in overall features D. expansus seems to be less variable than 
other species in the group, except when under very unfavorable environments where 
the individuals remain small. Young specimens are very light in color and more 
rounded. 

The lunule in Diplodon expansus is very narrow and sometimes concave. In the 
left valve there is a single pseudocardinal (occasionally with a small supplementary 
cusp) and 2 short and parallel cusps in the right valve. In older specimens I have 
observed transposition of teeth (an abnormality which has been studied by van der 
Schalie on North American naiads) with the single tooth on the right valve. Pseudo- 
cardinals are placed anteriorly to the umbo, under the lunule, and there is a long, 
curved, narrow and marginated interdentum. The lateral teeth are short but strong. 
All muscles scars are very well impressed. As a whole, the hinge plate differs from 
that of D. uruguayensis in which the teeth are closer to the D. delodontus type. Some 
females of D. expansus, when old and heavy, offer an aspect resembling D. uruguay- 
ensis, but the characteristics of the teeth denounces the difference. The mark of 
ligamental insertion is placed closer to the end of the laterals and the cartilage 
extends under the umbo. 

Of Unio guahybae Ihering (in litt.), which I included, following Haas and Bonetto, in 
the list of names under Diplodon expansus, most probably does not belong here. I 
have specimens labelled by Ihering from the Guahyba River (or Guaiba, according to 
Maria Cristina Mansur, of Porto Alegre, from whom I have also received excellent 
lots of this form) in which the hinge is of the D. rotundus Wagner type, with a sub- 
trapezoidal shape; it might constitute a valid form between D. rotundus rotundus and 
D. rotundus fontaineanus d'Orb.; however, it is still undescribed. 

An extreme southwestern locality for Diplodon expansus was registered on specimens 
of the Museo Argentino de Ciencias Naturales (Buenos Aires) collection, from the 
Ibicuy Island, on the Paraná River, Paraguay, 25 km east of Encarnación and south of 
Carmen. The specimens have the umbos mostly eroded, due to the rapid water of the 
Paraná River in that area. Apart from the relatively larger size, they are identical 
with those of the original lot of D. mogymirim, (see Figs. 19-21). The Ibicuy Island 
on the Upper Paraná should not be confused with the island of same name in the 
Paraná Delta. 



PARODIZ 267 

Diplodon paulista (Ihering 1893) 

Unio paulista Ihering, 1893: 93, pi. 4, fig. 7. 

Diplodon delodontus expansus, Haas, 1930: 192. Bonetto, 1964; 325; 1965: 44. 
Diplodon paulista, Simpson, 1900: 873; 1914: 1229. Ortmann, 1921: 501, pi. 46, 
fig. 1, pi. 47, fig. 1. Bonetto, 1961a: 14; 1961b: 49. Parodiz, 1968: 9, 18. 

For a complete, detailed description of this species, including anatomy and glochidia, 
see Ortmann (1921). 

Type Locality . Tieté River, at Piracicaba, Sâo Paulo, Brazil (Lectotype in Sencken- 
berg Museum; paratypes Carnegie Museum). Other materials in the Carnegie Museum 
are from Sapina, Sâo Sebastio, Mogy das Cruzes and Mogy Mirim, all of Sâo Paulo. 

This species differs from Diplodon expansus in its more elongated shape, being 
more depressed, with posterior margin more angulated and narrower front; it is also 
less solid, the periostracum is not marked, and it is green, not chestnut as in D. 
expansus, and the nacre is more bluish. Additional differences are: the smaller and 
more triangular pseudocardinals and the thinner and longer laterals with sharp edges 
reaching below the umbo and without noticeable interdentum. 

Ortmann did not compare this species with his Diplodon mogymirim (=D. expansus), 
assuming that the differences were obvious. It is sympatric with it and found at the 
same localities living together, for which any subspecific or ecological consideration 
of differences is out of order. 

The specimens I observed at the Senckenberg Museum (Nos. 3872 and 3873), types 
and paratypes, agree in all details with those in the Carnegie Museum studied by 
Ortmann, but are of larger size. 

SYNOPSIS OF DISTRIBUTION 

Species typical of the lower Parana and La Plata rivers: Diplodon delodontus 
delodontus, north to Paraguay; Diplodon delodontus wymani, La Plata River and its 
affluents in the Buenos Aires Provinces; Diplodon solisianus, west bank of La Plata 
River and affluents up to Santa Fe - now rare in Uruguay. 

Species typical of Southern Brazil up to Sao Paulo: Diplodon martensi, Rio Grande 
do Sul and Sâo Paulo (also eastern Uruguay); Diplodon expansus, Sâo Paulo (Rio 
Janeiro?) east to Paraguay; Diplodon paulista, Sâo Paulo. 

Species typical of Uruguay: Diplodon uruguayensis , Central and northern Uruguay 
into Rio Grande do Sul. In Uruguay, all species (except D. expansus and D. paulista) 
overlap. 

The La Plata River system, which includes the vast area of the Paraná-Paraguay- 
Uruguay drainages, did not come into existence (as we know it at present) until the 
Pleistocene epoch (see Parodiz, 1969: 34). Therefore, the expansion of Diplodon 
southwards and the correlative speciation was a very rapid process on which account 
the species still maintain very close affinity and overlapping areas, resulting in re- 
current crossbreeding. 

RESUMEN 

Las relaciones entre seis especies de Diplodon, pertenecientes al complejo super- 
específico de D. delodontus (Lam.), se estudiaron para aclarar el problema que plantea 
sus identificaciones. La completa revisión conchológica de cada especie demostró 
que varias de ellas -nominalmente consideradas sinónimos en trabajos previosdebe 
rehabilitarse. Las seis especies aqui reconocidas son: Diplodon delodontus (Lamarck 
1819); D. delodontus wymani (Lea 1860); D. uruguayensis (Lea 1860); D. martensi 
(Ihering 1893); D. expansus (Küster 1856); D. solisianus (d'Orbigny 1835); D. paulista 



268 PROC. FOURTH EUROP. MA LAC. CONGR. 

(Ihering 1893). 

La distribución comprende el sistema fluvial del Paraná, Uruguay y La Plata; desde 
que tal sistema -tal como lo conocemos hoy- se formó recién en el Pleistoceno, la 
ocupación del área y el proceso de especiación fueron de operación muy rápida e 
inmediata al Reciente, lo que explica la gran afinidad de constitución genética demos- 
trada por repetidos cruzamientos. Existe acusada simpatría en la superposición de 
grandes áreas de distribución en cada especie, lo que impide el reconocimiento de 
subespecies (excepto en el caso de Diplodon delodontus wymani); por otra parte, la 
co-habitación de un mismo nicho ecológico por distintas especies, demuestra que la 
"variaciones" frecuentemente consideradas ecológicas, no son tanto fenotípicas como 
genotípicas debido a hybridización. El concepto de superespecie es perfectamente 
aplicable al grupo de D. delodontus, siendo este monofilético y manteniendo sus especies 
tal afinidad como para permitir cruzamientos recurrentes. 

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PARODIZ 269 

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270 PROC. FOURTH EUROP. MALAC. CONGR. 

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MALACOLOGIA, 1973, 14: 271-285 

PROC. FOURTH EUROP. MA LAC. CONGR. 

DIE GATTUNG BYTHINELLA UND DIE GATTUNG MARSTONIOPSISIN 
WESTEUROPA, 1. WESTEUROPÄISCHE HYDROBIIDAE, 4 1 . (PROSOBRANCHIA) 

Hans D. Boeters 

Rumfordstr. 42, D-8 München 5, Deutschland 

(1) Bythinella 

1851 Les Bithinelles Moquin Tandon, J. Conchyliol. , 2: 237 [nom. nud.]. 

1855 Bythinella Moquin Tandon, Hist, natur. , 2: 515 und 516. Typus: Bulimus 

viridis Poiret, 1801. Typus wähl: Stimpson (1865: 44). 
1892 Bicarinatiana Fagot, Bull. Soc. Ramond, 27: 27-28 [nom. obi.]. Typus: 

Paludina bicarinata Des Moulins, 1827. Typuswahl: Fagot (1892: 28). 
1929 Brachypyrgula Polinski, Glas Srpske Kral. Akad. , 137: 153. Monotypus: 

Paludina bicarinata Des Moulins, 1827. 
1931 Pyrgobythinella Germain, Mollusques, 2:627. Monotypus: Hydrobia carin- 

ulata Drouet, 1868. 

Bemerkungen: Es wurden nur geringfügige anatomische Unterschiede zwischen 
viridis, dem Bythinella-Typus, einerseits und carinulata, dem Pyrgobythinella -Typus, 
sowie bicarinata, dem Brachypyrgula -Typus, andererseits ermittelt. Da auch eine 
befriedigende conchologische Abgrenzung von viridis und carinulata nach heutigen 
Kenntnissen nicht möglich ist, wird Pyrgobythinella als jüngeres Synonym von Bythi- 
nella s. str. angesehen. Das gleiche gilt für Brachypyrgula, da die conchologische 
Eigenartigkeit von bicarinata allein für eine Abtrennung von Bythinella s. str. nicht 
ausreicht. 

В. {B.) viridis 
Abb. 1, 24-25, 35 

1801 Bulimus viridis Poiret, Aisne: 45-46. Loe. typ.: "Le ruisseau qui tombe 
en cascade de la montagne au bas de laquelle est situe le moulin de Veau, 
proche Chartreuve" bei Chery-Chartreuve, Aisne. 

Kiemenlamellen: 19-20 (ВОЕ 386/1 -2çç, 11-12о*сС); Osphradium nicht hahnenkamm- 
förmig (ВОЕ 386/1-2 çç, 11-12сГсГ). - Darm: 1 Z-förmige Schlinge hinter dem Magen 
mit 8-9 Kotballen hinter der Schlinge (ВОЕ 386/1-2 çç); der U-förmige Knick hinter 
der Schlinge ist beim d* spitz V-förmig ausgebildet (ВОЕ 386/lld'). — Penis: in der 
Ruhelage etwa so lang wie die Drüsenrute (Abb. 25 = ВОЕ 386/11). —Weiblicher 
Genitraltrakt: Ovidukt vor der Einmündung des Recepta eulum seminis mit 1 Z -förmigen 
Schlinge, 1 Receptaculum seminis, Bursa copulatrix U-förmig (Abb. 24 = ВОЕ 386/1, 2). 

Untersuchtes Material und Vorkommen: ВОЕ 386 = Rheokrenen (11,5°C; mit Pota- 
mopyrgus jenkinsi) am Abluss der Fontaine St. Martin und Abfluss (9,5 °C) dieser 
Fontaine an der Strasse von Dravegny nach St. Gilles ca. 4,5 km nö. Chartreuve. 

Typen: Syntypen (?) MW/5, D/3. 

Verbreitung: viridis dürfte in Westeuropa der älteste Name eines Taxons der Gattung 
Bythinella sein. Die Art und ihre Verbreitung muss bis zu ihrer Wiederbeschreibung 
in dieser Arbeit als so gut wie unbekannt angesehen werden. Daran ändert es nichts, 



iSiehe 1: Avenionia, Arch. Molluskenk. , 96; 155-165; 2: Microna, Arch. Molluskenk. , 100: 113- 
145; 3: Corrosella, J. Conchyliol. ,108: 63-69. 

(271) 



272 PROC. FOURTH EUROP. MALAC. CONGR. 

dass für viridis nach ihrer Beschreibung durch Poiret überall aus Westeuropa Fundorte 
angegeben worden sind. Die Ermittlung der Verbreitung von viridis steht erst am 
Anfang, da bisher von viridis weder Typen abgebildet worden sind noch der Versuch 
unternommen wurde, sie vom locus typicus wiederzubeschreiben. Ihre Abgrenzung 
gegen die benachbarte carinulata ist problematisch (vgl. unter B. (B.) carinulata). 

Fundortkatalog (Abb. 35): Aisne: Barzy und Chartèves (Lallemant & Servain 1869: 
43) [49,0/3,5°]. - Chartreuve bei Chéry-Chartreuve (Poiret 1801: 45-46) [49,2/3,6°]. 

В. (B.) carinulata 
Abb. 2-5, 26-27, 35 

1801 Turbo gris eus Vallot, Exercise: 6 [nom. obl.]. Loe. typ.: "Fontaine de 
Champmol", Dijon, CÔte-d'Or (Vallot, 1827: 71). 

1868 Ну drobia carinulata Dr ouet, Mem. Acad. imp. Sei. Arts b. -L. Dijon, (2) 
14(1866/67): 122. Originalfundorte: "fontaine de Larrey, près Dijon (type)! 
fontaine des Chartreux, à Dijon! fontaine de Velars! source de la Norges! 
la Douix, à Châtillon-sur-Seine! [sämtlich CÔte-d'Or]. . .dans l'Aube et la 
Haute- Marne. . .de l'est, notamment de la Moselle. ■ 

1869 Paludinella turgidula Paladilhe, Rev. Mag. Zool. pure appl. , (2) 21: 275- 
277, T. 20, F. 1-2. Originalfundorte: "Outre la localité de Billy-lès- 
Chanceaux (CÔte-d'Or). .. aussi dans le département de l'Aube, aux environs 
de Bar-sur-Seine et des Riceys. " 

1876 Paludinella scalarina Paladilhe, Rev. Sei. natur. , 5: 334-335. Loe. typ.: 

"près de Châtillon-sur-Seine (CÔte-d'Or). " 
1882 Bythinella túrgida Locard, Catalogue: 227. 
1893 Bythinella burgundina Locard, Conchyliologie: 80. Loc. typ.: "dans les 

puits de Châtillon-sur-Seine (CÔte-d'Or). " 
1931 Bythinella (Pyr goby thinella) carinulata, Germain, Faune, 2: 628. 

Synonymie: Nach dem Studium von Syntypen von burgundina und scalarina und 
Topotypen von turgidula sind diese jüngere Synonyme von carinulata (vgl. Abb. 2-5); 
dafür spricht auch die weite Verbreitung, die Drouet für carinulata angibt. Hingegen 
handelt es sich nach dem Studium von Topotypen von cylindracea Paladilhe, 1869 
[Belgrandia] und Syntypen von lanceolata Locard, 1893 [Belgrandia], riparia Locard, 
1893 [Belgrandia], sequanica Paladilhe, 1870 [Belgrandia] und tricassina Locard, 1893 
[Belgrandia] vermutlich um eine andere Art. Offen bleibt, um was es sich bei bour- 
guignati Locard, 1893 (: 88) [Bythinella] non bourguignati Locard, 1884 [Paulia] 
(1893: 92) handelt. 

Kiemenlamellen: 11-12 beicT сГ (ВОЕ 148/11-12), 21-22 bei ç ? (ВОЕ 148/1-3); Osphra- 
dium nicht hahnenkammförmig (ВОЕ 148/1-3 ^ ç). — Penis: in der Ruhelage etwa so 
lang wie die Drüsenrute (Abb. 27a-b = ВОЕ 148/12 bzw. 11). — Weiblicher Genital- 
trakt: Ovidukt vor der Einmündung des Receptaculum seminis mit 1 Z -förmigen 
Schlinge, 1 Receptaculum seminis, Bursa copulatrix J-förmig (Abb. 26 = ВОЕ 148/ 
1,2). 

Untersuchtes Material: ВОЕ 148 = Quellteich in Norges-la-Ville, CÔte-d'Or. 

Typen: carinulata: Syntypen nicht ermittelt, Topotypen ВОЕ 148 (Norges), 277 a-b 
und 290 a (Verlars); griseus: Syntypen nicht ermittelt; turgidula: Syntypen PA, Topo- 
typen ВОЕ 144 (Bar-sur -Seine); scalarina: Lectotypus PA (Etiketten: "Paludinella 
n.sp. Châtillon s. Seine Boutigny d." und "Paludinella scalarina Pal. 1876 Châtillon s. 
Seine Bout. d. w ); burgundina: Lectotypus MP und Paralectotypen MP/3. 

Vorkommen: Limnokrenen. 

Verbreitung: CÔte-d'Or, Yonne und Aube. Die Abgrenzung gegen viridis ist proble- 
matisch; beispielsweise will Drouet (1868: 121) viridis im Verbreitungsgebiet von 



ВОЕ TE RS 



273 




ABB. 1. Bythinella viridis (Syntypus (?) von Bulimus viridis Poiret; D). Chéry-Chartreuve, Aisne. 

ABB. 2-5. Bythinella carinulata. Abb. 2. (Topotypen von Hydrobia carinülata Drouet; ВОЕ 
148). Norges-la-Ville, Côte-d'Or. Abb. 3. (Lectotypus von Bythinella burgundina Locard; MP). 
Châtillon-sur-Seine, Côte-d'Or. Abb. 4. (Lectotypus von Paludinella scalarina Paladilhe; 
PA). Châtillon-sur-Seine, Côte-d'Or. Abb. 5. (Topotypen von Paludinella turgidula Paladilhe; 
ВОЕ 144). Bar-sur-Seine, Aube. 

ABB. 6. Bythinella bicarinata (Topotypus von Paludina bicarinata Des Moulins; ВОЕ 289). 
Couze-et-St. -Front, Dordogne. 

Vergrösserung 1:15. 



carinulata und wollen Lallemant & Servain (1869: 43) turgidula = carinulata im Ver- 
breitungsgebiet von viridis gefunden haben. 

Fundortkatalog (Abb. 35): Côte-d'Or: Quelle in Beaune (ВОЕ 152, 47°Г 55"/4°49' 35") 
[47,0/4,8°]. - Velars -sur -Ouche (Drouet 1868: 122) [47,3/4,9°]. - Dijon (Vallot 1827: 
71, viridis; Drouet 1868: 122) [47,3/5,0°]. - Norges-la-Ville (Drouet 1868: 122) 
[47,4/5,0°]. - Billy-lès-Chanceaux (Paladilhe 1869: 276, turgidula) [47,5/4,7°]. - 
Châtillon-sur-Seine (Vallot 1827: 71, viridis; Drouet 1868: 122; Boutigny nach Pala- 
dilhe 1876: 335, scalarina; Beaudouin nach Locard 1893: 80, burgundina) [47,8/4,5 ]. 
- Yonne: Châtel-Censoir (Caziot 1907: 253) [47,5/3,6°]. - Aube: Riceys (Paladilhe 



274 PROC. FOURTH EUROP. MALAC. CONGR. 

1869: 276, turgidula) [47,9/4,3°]. - Fontaine du Cris zw. Jully-sur-Sarce u. Ville- 
morien (ВОЕ 142); Quelle zw. Polisot u. Bar-sur-Seine links der Seine (ВОЕ 143) 
[48,0/4,3°]. - Bar-sur-Seine (Paladilhe 1869: 276, turgidula) [48,1/4,3°]. - Quellen 
im Val-d' Ariette n. Arsonval (ВОЕ 140) [48,2/4,6°]. -Sonstiges: Haute-Marne und 
Moselle (wo? Drouet 1868: 122). 

В. {В.) reyniesii 
Abb. 9-13, 30-32 

1851 Hydrobia reyniesii Dupuy, Hist, natur. , 5: 567-569; 6: T. 28, F. 6. Ori- 
ginalfundorte: "environs de Cauterets, au Four à chaux..., près de Ma- 
hourat, près du lac de Gaube, . . о dans la vallée du lac d'Estom. . . aux en- 
virons de Bagnères-de-Bigorre", Hautes- Pyrénées. 

1874 Paludinella baudoni Paladilhe, Ann. Sei. natur. , Zool. , (6) 1: 32-33, T. 3, 
F. 9-10. Loc. typ.: "à la source de la Pique, port de Venasque (Gironde 
[!])", Haute- Garonne. 

1875 Paludinella andorrensis Paladilhe, Ann. Sei. natur., Zool., (6)2:13-14, 
T. 21, F. 24-26. Originalfundorte: "dans le val d'Andorre, ... en Catalogne, 
dans les environs de Ribas. " 

1877 Paludinella darrieuxii Folin & Berillon, Bull. Soc. Borda Dax, 2: 208, T. 
3, F. 3-5. Loc. typ.: "ad fontem nomine Bente d'Arneguy [Fontaine de 
Bessie nach Granger 1897: 259] circum St- Jean- Pied-de- Port", Basses- 
Pyrénées. 

1890 Paludinella darrieuxii, Folin, Naturaliste, (2) 12: 200, 2 Abb. 

1891 Bythinella baudoniana Bofill, Cron. cient. , 318: 7. 

Bemerkungen: Wie ein Vergleich des Lectotypus von darrieuxii mit der Original- 
abbildung von Folin und Berillon zeigt, wurde darrieuxii von diesen Autoren unzutreffend 
abgebildet. Nach einem conchologischen und anatomischen Vergleich und aufgrund des 
Vorkommens handelt es sich bei darrieuxii um ein jüngeres Synonym von reyniesii. 
Auch andorrensis und baudoni sind nach dem Studium von Syntypen als jüngere Synonyme 
von reyniesii anzusehen. 

Kiemenlamellen: 17-20 bei dV (ВОЕ 195/11, 362/11-12), 20-22 bei $ç (ВОЕ 195/1, 
362/1-2); Osphradium hahnenkammförmig (ВОЕ 195/1 çund 11 çf, 362/llcT). — Darm: 
Bei cTc/undç^l Z-förmige Schlinge hinter dem Magen (ВОЕ 362/1-2 ççund 11-12 efe?) 
mit (etwa) 11 Kotballen hinter der Schlinge (ВОЕ 362/13 0*); bei dWor der Spitze des 
ruhenden Penis Richtung After 1 V-förmiger Darmknick (ВОЕ 362/11-13).— Penis: In 
der Ruhelage fast so lang oder kürzer als die Drüsenrute (Abb. 30 = ВОЕ 195/П, 
Abb. 32 = ВОЕ 362/11, 13). - Weiblicher Genitaltrakt: Ovidukt vor der Einmündung 
des Receptaculum seminis mit 1 Z -förmigen Schlinge, 1 Receptaculum seminis, 
Bursa copulatrix J-förmig (Abb. 31 = ВОЕ 362/1, 2). 

Untersuchtes Material: ВОЕ 195 = Quelle im Thermenpark von Bagnères-de-Bigorre, 
Hautes-Pyrénées; ВОЕ 362 = gefasste Quelle ca. 300 m nö. der Kirche rechts an der 
Strasse nach St.-Jean-Pied-de-Port in Arnéguy, Basses-Pyrénées. 

Typen: reyniesii: Syntypen nicht ermittelt, Topotypen ВОЕ 195-197 und 288 (alle 
Bagnères-de-Bigorre); baudoni: Lectotypus PA und Paralectotypus PA/l (Etiketten: 
"Paludinella Baudoni (Gironde)" und "Paludinella Baudoni PAL. 1873 Source de la 
Pique Port de Venasque (Gironde) Ind. Baud, d."); andorrensis: Syntypen BOU/zahl- 
reich; darrieuxii: Lectotypus BE (Etiketten: "Fontaine Bente d'Arneguy près St. 
Jean Pied de Port" und "Paludinella darrieuxii Fol. et Beri." und "Lecto Type [ver- 
mutlich unveröffentlicht] *), Topotypen (?) ВОЕ 362-363. 

Vorkommen: Rhoekrenen auf vorzugsweise kalkarmen Formationen (11,5°C, ВОЕ 
195, gelegentlich mit Potamopyrgus jenkinsi und Microna sp., ВОЕ 362-363). 

Verbreitung: Über die Pyrenäen und vermutlich das Massif Central (Abb. 23, nörd- 
lich bis an die Côte-d'Or?) weit verbreitet. 



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275 




ABB. 7-8. Bythinella pyrenaica. Abb. 7. (Die F. 12 von Pyrgula pyrenaica Bourguignat in 
Bourguignat, 1861: T. 15 wurde auf 57 mm vergrö'ssert, was einer Vergrösserung der natür- 
lichen Gehäuselänge gemäss T. 15, F. 11 im Verhältnis 1 : 15 entspricht). Abb. 8. (Lecto- 
typus von Pyrgula pyrenaica Bourguignat; BOU). Bagnères-de-Bigorre, Hautes- Pyrenees. 

ABB. 9-13. Bythinella reyniesii. Abb. 9. (Die F. 4 von Paludinella darrieuxii Folin & Berillon 
in Folin & Berillon, 1877: T. 3 wurde auf 38 mm verkleinert, was einer Vergrösserung des 
nach Folin & Berillon, 1877: 208 "2 mm 5" langen Gehäuses im Verhältnis 1 : 15 entspricht). 
Abb. 10. (Lectotypus von Paludinella darrieuxii Folin & Berillon; BE). Arneguy, Basses- 
Pyrenees. Abb. 11. (Topotypen von Hydrobia reyniesii Dupuy; ВОЕ 195). Bagnères-de- 
Bigorre, Hautes- Pyrenees. Abb. 12. (Syntypen von Paludinella andorrensis Paladilhe; BOU). 
Les Escaldes, Andorra. Abb. 13. (Lectotypus von Paludinella baudoni Paladilhe; PA). Port 
de Venas que, Haute- Garonne. Vergrösserung 1: 15. 



В. (В.) bicarinata 
Abb. 6, 28-29 

1827 Paludina bicarinata Des Moulins, Bull. Hist, natur. Soc. linn. Bordeaux, 
2: 26-27, T. Loc. typ.: "dans la petite rivière de Couze, près Lalinde, 
arrondissement de Bergerac", Dordogne. 

1838 Páludina tricarinata Potiez & Michaud, Galerie, 1: 256, T. 26, F. 21-22 
[nov. nom. pro bicarinata] . 

1892 Bythinella (Bicarinatiana) bicarinata, Fagot, Bull. Soc. Ramond, 27: 27-28. 

1929 Brachypyrgula bicarinata, Polinski, Glas Srpske Kral. Akad. , 137: 153. 



276 PROC. FOURTH EUROP. MALAC. CONGR. 

Kiemenlamellen: 20 (ВОЕ 366/3 ç , 11-12 dtf). — Penis: in der Ruhelage etwas 
länger als die Drüsenrute (Abb. 29 а = ВОЕ Збб /ll, Abb. 29b = ВОЕ 366/12). - Weib- 
licher Genitaltrakt: Ovidukt vor der Einmündung des Receptaculum seminis mit 1 
gelblichen Z -förmigen Schlinge, 1 Receptaculum seminis, proximaler Teil der An- 
hangdrüse relativ schwach ausgebildet (Abb. 28 = ВОЕ Збб /l, 2). 

Typen: Syntypen nicht ermittelt, Topotypen D/l (Dupuy 1851: 578, Astre 1921: 262) 
und ВОЕ 289 und 366. 

Untersuchtes Material, Vorkommen und Verbreitung: Bisher nur vom locus typicus, 
einer Limnokrene (Waschhaus) am Couze-Ufer, bekannt (18°C). 

B. pyrenaica 
Abb. 7-8 

1861 Pyrgula pyrenaica Bourguignat, Rev. Mag. ZooL pure appl. , (2) 13: 530- 
531, T. 15, F. 11-13. Loc. typ. (restr. ): "dans la fontaine ferrugineuse 
de Bagnères-de-Bigorre (Hautes- Pyrenees ). " 

Bemerkungen: Durch Polinski (1929: 154) wurde pyrenaica neben stancovici Polinski, 
1929, den Typus von Micropyrgula, gestellt. Die Anatomie von stancovici wurde von 
Radoman (1955) beschrieben. Bei pyrenaica handelt es sich jedoch um keine Micro- 
pyrgula, sondern um eine Bythinella, die von Bourguignat irreführend abgebildet 
wurde; der Lectotypus zeigt den für Bythinella typischen schräg aufsitzenden Apex. 

Unklar ist, um was es sich bei paludestrinoid.es Paladilhe, 1869 [Hydrobia] und 
bigorriensis Paladilhe, 1869 [Belgrandia] handelt, die beide wie pyrenaica in einer 
"source ferrugineuse" bzw. "fontaine ferrugineuse, près de Bigorre (Hautes-Pyrénées)" 
gefunden wurden. 

Typen: Lectotypus BOU. 

Vorkommen und Verbreitung: pyrenaica ist seit ihrer Beschreibung an den von 
Bourguignat angegebenen Orten nicht wiedergefunden worden. Die Quelle, zu der die 
Avenue de la Fontaine Ferrugineuse in Bagnères-de-Bigorre führt, beherbergt keine 
Bythinella; in Rheokrenen unterhalb dieser Quelle findet man nur reyniesii. 

BESTIMMUNGSSCHLÜSSEL 

Mit diesem Schlüssel wird der Versuch unternommen, innerhalb einer Gattung der 
Hydrobiidae eine Arten-Bestimmung ausschliesslich aufgrund anatomischer Merkmale 
durchzuführen. Der Schlüssel kann jedoch nicht mehr als eine Anregung geben, da die 
Konstanz der ihm zugrundeligenden Merkmale ungewiss ist. 

1 Bursa copulatrix etwa oval bicarinata 

- Bursa copulatrix etwa wurstförmig 2 

2 Bursa copulatrix etwa U-förmig viridis 

- Bursa copulatrix etwa J-förmig 3 

3 Anhangdrüse des ç distal erst im letzten Viertel ab Einmündung des Ovidukts 
deutlich verjüngt, ruhender Penis nicht kürzer als die Drüsenrute carinulata 

- Anhangdrüse des ç distal etwa ab Einmündung des Ovidukts spitz auslaufend, 
ruhender Penis kürzer als die Drüsenrute reyniesii 

(2) Marstoniopsis 

1936 Marstoniopsis van Regieren Altena, Basteria, 1: 64-73. Typus: Hydrobia 
steinii Martens, 1858. Typuswahl: van Regteren Altena (1936: 69). 



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277 




ABB. 14-17. Marstoniopsis scholtzi. Abb. 14. (Topotypus von Hydrobia scholtzi A. Schmidt; 
SMF 114 559). Marienau, Schlesien. Abb. 15. (SMF 114 527). Bach bei Tegel (Berlin). 
Abb. 16. (Syntypus von Paludinella armoricana Paladilhe; PA). Nantes, Loire- Atlantique. 
Abb. 17. (Paratypus von Amnícola steinii pallida Krausp; SMF 142 367). Kostivere, Estland. 

ABB. 18. Marstoniopsis insubrica (Topotypus von Paludina insubrica Küster; ВОЕ 128 ex 
Wüthrich). Muzzano, Tessin. 

ABB. 19-20. Bythinella abbreviata. Abb. 19. (Die F. 53 von Paludina abbreviata Michaud in 
Michaud, 1831: T. 15 wurde auf 35 mm vergrössert, was einer Ver gross erung des in F. 52 in 
natürlicher Grösse dargestellten Gehäuses im Verhältnis 1 : 15 entspricht). Abb. 20. (Syn- 
typus von Paludina abbreviata Michaud; PA). Lyon, Rhône. 

ABB. 21. Bythinella sp. (ВОЕ 413 с ex Geissert). Arbois, Jura. 

ABB. 22. Bythinella pupoides (Topotypus von Paludinella /myoides Paladilhe; ВОЕ 384). Thoiry, 
Ain. 

ABB. 23. Bythinella reyniesii (?) (Das von Germain, 1931: T. 19, F. 549 in einer Vergrös- 
serung von "x 20" abgebildete Gehäuse wurde auf 44 mm entsprechend einer Vergrösserung im 
Verhältnis 1:15 verkleinert). Mont d'Or Lyonnais, Rhône. 

Vergrösserung 1:15. 



278 PROC. FOURTH EUROP. MALAC. CONGR. 

Differenzierende Merkmale: Anders als bei Bythinella (Bregenzer 1915: 252) mit 
einem schwefelgelben Fleck oberhalb der Augen (E. A. Smith 1901: 192, Van Regieren 
Altena 1936: 65, 69), Kieme der ç ç mit etwa 27 Lamellen (vgl. unten) gegenüber 22 
und weniger bei Bythinella (vgl. oben und Bregenzer 1915: 246, T. 16 F. 2 ç), Drüsen- 
rute (vgl. unten und Van Regieren Altena 1936: 73, Abb. 3a) gedrungener als bei 
Bythinella (vgl. oben und Literaturzusammenstellung in Boeters 1970: 117), der Ovidukt 
ist nach eigenen Untersuchungen anders als bei Bythinella in unübersichtlicher Weise 
nach Annäherung an die Anhangdrüse mit dieser verwachsen (wobei bereits Krull 
1935: 444 die Struktur von Bursa copulatrix und Receptaculum seminis nur z. T. auf- 
klären konnte), Unterschiede im Nervensystem gegenüber Bythinella bei Krull (1935: 
424), Laich nicht wie bei Bythinella einfach-linsenförmig (Lauterborn 1904: 86, 
Bregenzer 1915: T. 16, F. 13, Jungbluth 1971: Abb. 31a-c), sondern mit einem Kiel 
(Jackson & Taylor 1904: 10, Abb. 3-5, Van Regieren Altena 1936: 65, 75, Abb. 1), 
Vorkommen in sauerstoffärmerem Wasser als Bythinella (scholtzi wurde von Ziegeler 
1935: 57 im Aquarium gezüchtet). 

M. scholtzi 
Abb. 14-17, 33, 36 

1850 Bythinia acuta, Stein, Berlin: 95, non T. 3, F. 5. 

1853 Paludina sp. , Scholtz, Schlesien, 2. Aufl. , Suppl. : 13-14. 

1856 Hydrobia scholtzi A . Schmidt, Z. ges. Naturw. , 8: 158. Loc. typ.: "Wie- 
sengräben zwischen Breslau und Marienau". 

1857 Hydrobia scholtzi, A. Schmidt, Verzeichnis: 42. 

1858 Hydrobia steinii Martens, Arch. Naturgesch. , 24: 183-184, T. 5, F. 9. 
Originalfundorte: "am Ufer des Tegelsees zwischen Berlin und Spandau" 
und "in der Havel bei Pichelsberg". 

1869 Paludinella armoricana Paladilhe, Rev. Mag. Zool. pure appl. , (2) 21: 
278-279, T. 20, F. 5-6. Loc. typ.: "dans l'Erdre, près de Nantes", 
Loi re- Atlantique . 

1901 Paludestrina taylori E. A. Smith, Ann. Mag. natur. Hist. , (7) 7: 191-192. 
Loc. typ.: "canal at Dukinfield, Cheshire". 

1936 Amnícola steinii pallida Krausp, Eesti loodus.: 196-200. Loc. typ.: 
"Estonia, the district of Harjumaa, Kostivere, at the beginning of the sub- 
terranean river of the Jöelähtme- River". 

Bemerkungen: Stein führte 1850 Funde von "Bythinia acuta Drap." bei Berlin an, 
Scholtz 1853 "Paludina spec, nova?" aus der Umgebung Breslaus. Beide Angaben 
hatten Neubeschreibungen zur Folge. Jedoch wurde das Scholtzsche Material schon 
1856 durch A. Schmidt mit dem Namen s choltz i belegt, während die Beschreibung von 
steinii mit dem Steinschen Material durch Martens erst 1858 erfolgte. Clessin 
erkannte (1884: 480), dass es sich um Synonyme handelt; er gab jedoch dem jüngeren 
Namen steinii den Vorrang: "Scholtz hat seine Beschreibung wahrscheinlich nach 
unvollendeten Exemplaren entworfen. " Damit wurde die bis zum heutigen Zeitpunkt 
vor allem im deutschsprachigen Schrifttum verbreitete Unterdrückung des nomen- 
klatorisch gültigen und älteren Namens scholtzi begründet. Hingegen wird in der 
jüngeren englischen Literature die Art richtig als scholtzi geführt (z.B. Census 1951: 
179, Fretter & Graham 1962: 642, Ellis 1969: 271). 

Radula: (?Lindström 1868: T. 3, F. 9, der Penis F. 8 zeigt keine Drüsenrute! 
Johansen 1918: Abb. 10, T. Benthem Jutting 1933: Abb. 68, Krull 1935: 413, Van Reg- 
ieren Altena 1936: 66, Abb. 2, Verdcourt 1948: Abb. 8-11). - К1етеп1атеиеп:сГсГ21 
(ВОЕ 274/11), $$ 28 (ВОЕ 274/1-2). — Penis: Drüsenrute etwa halb so lang wie der 
Penis (Van Regteren Altena 1936: 73, Abb. 3a, Abb. 33 = ВОЕ 274/1 1, 12). - Weiblicher 
Genitaltrakt: Krull konnte die Struktur von Bursa copulatrix und Receptaculum seminis 



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279 




ABB. 24-25. Bythinella viridis (ВОЕ 386). Zwischen Chery-Chartreuve und St. 

Gilles, Aisne. ABB. 26-27. Bythinella carinulata (Topotypen von Hydrobia cari- 

nulata Drouet; ВОЕ 148). Norges-la- Ville, Côte-d'Or. ABB. 28-29. Bythi- 

nella bicarinata (Topotypen von Paludina bicarinata Des Moulins; ВОЕ 366). Couze-et-St. -Front, 
Dordogne. ABB. 30-32. Bythinella reyniesii. Abb. 30. (Topotypus von Hydrobia reyniesii 
Dupuy; ВОЕ 195). Bagnères-de-Bigorre, Hautes- Pyrenees. Abb. 31-32. (Topotypen (?) von 
Paludinella darrieuxii Folin & Berillon; ВОЕ 362). Arneguy, Bass es- Pyrenees. ABB. 33. 
Marstoniopsis scholtzi (ВОЕ 274 ex Meier-Brook). Langsee (Kiel-Elmschenhagen). ABB. 34. 
Marstoniopsis insubrica (SMF 4 649). Lago Maggiore. 

Vergleichsstrecke 0,25 mm. 



280 PROC. FOURTH EUROP. MALAC. CONGR. 

nicht völlig aufklären (1935: 444); nach eigenen Untersuchungen ist der Ovidukt nach 
Annäherung an die Anhangdrüse in unübersichtlicher Weise mit dieser verwachsen 
(ВОЕ 274/1). 

Untersuchtes Material: ВОЕ 274 = Langsee, Kiel-Elmschenhagen, Meier-Brook leg. 

Typen: scholtzi: Topotypen SMF 114 559/11; steinii: Syntypen nicht ermittelt; 
armoricana: Syntypen PA/zahlreich; pallida: Syntypen SMF 142 367/7. 

Verbreitung: 

(1) Grossbritannien. Die in der Literatur verbreitete Ansicht, dass scholtzi aus 
Nordamerika nach Europa eingeschleppt worden sei, geht auf E. A. Smith (1901: 191) 
zurück und trifft nicht zu. Diese irrige Ansicht wurde dadurch begünstigt, dass E. A. 
Smith die bis 1901 rezent nur vom Kontinent bekannte scholtzi beim Erstnachweis für 
Grossbritannien nicht erkannte und als taylori neu beschrieb. Smith's Ansicht wurde 
in jüngster Zeit von D. W. Taylor (1966: 173) und Ellis (1969: 271) richtig gestellt; 
taylori wurde von E. A. Smith anhand rezenten Materials beschrieben, — nicht nach 
einem fossilen Fund, wie S. G. A. Jaeckel(1962: 49, 1967: 97 Fussnote 112) entnommen 
werden muss, wenn er schreibt: "+ Amnícola taylori (Smith 1901). . . ausgestorben u. 
durch. .. [Mars toni ops is steinii - scholtzi] ersetzt.* Ferner ist an diesem Zitat 
richtigzustellen, dass nach Van Regieren Altena (19 36: 70) und Ellis (1969: 271) scholtzi 
[und nicht taylori]] im Holozän in Grossbritannien erloschen ist, jedoch durch "reintro- 
duction from its area in the northwestern part of the European continent in historical 
time" (Van Regieren Altena 1936: 70, "recent importation" nach Ellis 1969: 271) 
heute in Grossbritannien wieder vorkommt. 

Ein Argument, das gegen dieses zwischenzeitliche Erlöschen sprechen könnte, ist 
die Tatsache, dass von Mercuria sp. (=Pseudamnicola confusa auct.) bisher nichts 
analoges berichtet wird; diese Art kommt gleichfalls in Grossbritannien vor und be- 
gleitet scholtzi stellenweise, — zumindest auf dem westlichen europäischen Kontinent 
(Paladilhe 1869: 279). 

(2) Frankreich. Marstoniopsis wurde bisher aus Frankreich noch nicht rezent ange- 
geben. Jedoch stellt armoricana ein Synonym von scholtzi dar; armoricana wurde am 
locus typicus mit sarahae Paladilhe, 1869 [Amnícola] - Mercuria sp. vergesellschaftet 
angetroffen. Nach dem Gehäuse kann es sich auch bei curta Paladilhe, 1874 [Paludinella] 
um ein Synonym von scholtzi handeln. 

Fundortkatalog (Abb. 36): rezent: Loire-Atlantique: Nantes (Letourneux nach Paladilhe 
1869: 279, armoricana) [47,2/-l,6°]; pleistozän: Charente-Maritime: Celles-sur-le-Ne 
(Bourdier 1942: 473, steinii) [45,6/-0,4°]. — Dordogne: Condat [-le-Lardin oder -sur- 
Tricou oder -sur-Vézère?] (Bourdier 1942: 473, steinii). 

M. insubrica 
Abb. 34, 36 

1853 Paludina insubrica Küster, Paludina, 2: 77-78, T. 13, F. 20-21. Loc. 
typ: "Lago di Muzano bei Lugano". 

1859 Bythinia insubrica stabilei Stabile, Atti Soc. geol. res. Milano, 1(1855/59): 
167 und 182. Loc. typ.: "lago di Muzzano". 

1968 Marstoniopsis insubrica, Boeters, Mitt. bad. Landesver. Naturk. Natur- 
schutz, NF 9: 755 und 765. 

Bemerkungen: Die von Boeters (1968: 765) vertretene Auffassung, dass insubrica 
nicht wie bisher (Alzona & Alzona Bisacchi 1939: 143, Toffoletto 1964: 209) bei Pseud- 
amnicola, sondern bei Marstoniopsis einzuordnen ist, wird folgendermassen begründet: 
insubrica weist (anders als lucensis, der Typus von Pseudamnicola) wie scholtzi, der 
Typus von Marstoniopsis, einen schräg aufsitzenden Apex und eine Drüsenrute am 
männlichen Kopulationsorgan auf; auch kommt insubrica wie scholtzi in stehenden 



ВОЕ TE RS 



281 



У 



J 



\ о 



*~o 



'.'ГХ-^^л 



"V- ' 



. VI 



riefte.,. 




Г' 

caripufcrtq g \ 



pupoides 



Û< 




ABB. 35. Verbreitungsgebiete von By thinella viridis, В. carinulata und В. pupoides. 
dung beruht auf den Fundortkatalogen, vgl. die Erläuterungen unter (4). 



Die Abbil- 



Gewässern vor. 

Es bleibt zu klären, ob scholtzi nicht nur eine geographische Rasse von insubrica 
darstellt; eine Verbindung zu den s choltzi -Vorkommen des Balkans kann nicht von 
vornherein ausgeschlossen werden. Von S. H. Jaeckel & Klemm & Meise (1958: 175) 
wird scholtzi als nord-, mittel- und (nicht etwa Südost- sondern glatt:) südeuropäisch 
bezeichnet. (Bei weiterer Bearbeitung südeuropäischer Marstoniopsis -Vorkommen 
wären auch lacustris Hadzisce, 1958 [Bythinella] und macedónica Hadzisce, 1958 
[Belgrandia], von welcher der Autor die zapfenartige [!] Drüsenrute hervorhebt, zu 
überprüfen.) 

Radula: Mittelplatte mit 2 Lateraldentikeln (ВОЕ 95/l). — Kiemenlamellen: (etwa) 
3 vor, 12 am, 6 hinter dem Osphradium Richtung Mantelrand, insgesamt (etwa) 21 bei 
tfcf (SMF 4 649/1 <3). — Penis: Drüsenrute etwa halb so lang wie der Penis (Abb. 34 = 
SMF 4 649/1). 

Untersuchtes Material: ВОЕ 95 = Lago di Muzzano, Wüthrich leg., SMF 4 649/10 = 
Isola dei Pescatori im Lago Maggiore, Gaschott leg. 

Typen: insubrica und stabilei: Topotypen ВОЕ 95. 

Verbreitung: Südalpenrandzone. 

Fundortkatalog (Abb. 36): Schweiz: Lago di Muzzano (Stabile nach Küster 1853: 78, 
Stabile 1859: 167, Wüthrich nachBoeters 1968: 765) [45,9/8,9°]. -Italien: Lago Maggiore 



282 PROC. FOURTH EUROP. MALAC. CONGR. 

(Imhof 1901: 58, cylindrical Gaschott 1931: 35, Bythinella sp., Nocentini nach Toffoletto 
1964: 209) |45,9/8,5° und 46,0/8,6°]. - Lago di Garda bei San Vigilio (Gittenberger 
in litt.) [45,5/10,7°]. - Castel Goffredo (Genist) (F) [45,2/10,4°]. - Lago di Levico 
(SMF 142 364, steinii) [46,0/ll,2°l. 

(3) Bythinella oder Marstoniopsis abbreviata 
Abb. 19-20 

1831 Paludina abbreviata Michaud, Complément: 98, T. 15, F. 52-53. Loe. 
typ. : "Lyon, dans les alluvions du Rhône. " 

Bemerkungen: Zur Anregung der Diskussion um die Identifizierung von abbreviata 
wird im folgenden die Frage aufgeworfen, ob es sich möglicherweise um einen Ver- 
treter von Marstoniopsis handelt. 

Aufgefundene Syntypen (Abb. 20) stimmen gut mit Michaud' s Abbildung (Abb. 19) 
überein. Sie lassen sich bisher keiner Bythinella im Einzugsgebiet der Saône und 
Rhône bei Lyon zuordnen: - reyniesii (?, Abb. 23) der Ausläufer des Massif Central 
rechts der Saône und Rhône bei Lyon (Fischer 1880: 298 und 1885: 307, Locard 1877: 
515, viridis, Germain 1931: XII, T. 19, F. 549 und XIV, T. 23, F. 595, brevis) kommt 
abbreviata nicht nahe, bezüglich des Habitus und Vorkommens auf vorzugsweise 
kalkarmen Formationen eher dunkeri; - carinulata (Abb. 2-5) unterscheidet sich 
durch seine kantigen Umgänge und kommt nach heutigem Wissen nicht sehr nah an 
Lyon heran (Abb. 35); - pupoides (Abb. 22) hat schlankere Gehäuse und kommt nach 
gegenwärtigen Kenntnissen gleichfalls nicht sehr nah an Lyon heran (Abb. 35 auf 
Basis von Boeters 1968: 763, Abb. 72); auch eine weiterer von Geissert im Jura 
(Abb. 35 leeres Kästchen) gesammelte Bythinella {-viridis? Abb. 21), deren artliche 
Zuordnung noch zweifelhaft ist, kommt nicht in Betracht. 

Die aufgefundenen Syntypen zeigen vielmehr einen Marsíom'o/>s¿s-ahnlichen Habitus 
(vgl. Abb. 14-16 mit 20). Man könnte daran denken, dass abbreviata im Gebiet der 
Seenplatte (Les Dombes) zwischen Saône und Rhône nördlich Lyon vorkommt. Dazu 
machte Ogerien (1863: 544) in seiner Histoire naturelle du Jura unter dem Namen 
viridis die bemerkenswerte und bisher ungeklärte Angabe: "plaine, AC [assez com- 
mune]". 

Typen: Syntypen PA/6 (Etikett: "Paludinella abbreviata Jura typus ex auetore"). 
In Lyon (Forcart 1959: 7, Dance 1966: 294) und Brive-la-Gaillarde (Collot 1911: 94) 
wurden keine Syntypen ermittelt. 

NAMEN UND TYPUSFESTLEGUNGEN 

In dieser Arbeit werden folgende Namen erwähnt (in ihr festgelegte Typen sind in 
Klammern angegeben): andorr ensis, armoricana, baudoni (Lectotypus), baudoniana, 
bicarinata, bigorriensis, bourguignati [Bythinella non Paulia], burgandina (Lectotypus), 
carinulata, curta, cylindracea, darrieuxii (Lectotypus), griseus, insubrica, lanceolata, 
pallida, paludestrinoides, pupoides, pyrenaica (Lectotypus), reyniesii, riparia, scala- 
rina (Lectotypus), scholtzi, sequanica, stabilei, steinii, taylori, tricarinata, tricassina, 
túrgida, turgidula und viridis. 

Fundortkataloge: Bei der Angabe der geographischen Koordinaten und bei der 
Kartographierung (Abb. 35-36) wurde das von Boeters (1968: 756, 1970: 114) gewählte 
System benutzt. 

Sammlungen: 

BE = Sammlung Berillon, Musée d'Histoire Naturelle, Bayonne (Frankreich); 
ВОЕ = Sammlung Boeters, München (Deutschland); BOU = Sammlung Bourguignat, 
Muséum d'Histoire Naturelle, Genève (Schweiz); D = Sammlung Dupuy, Muséum 
d'Histoire Naturelle, Toulouse (Frankreich); F = Sammlung Falkner, München (Deutsch- 



BOETERS 



283 




ABB. 36. Verbreitungsgebiete von Marstoniopsis scholtzi und M. insubrica. 
beruht auf den Fundortkatalogen, vgl. die Erläuterungen unter (4). 



Die Abbildung 



land); MP* = Muséum National d'Histoire Naturelle, Paris (Frankreich); MW = Natur- 
historisches Museum, Wien (Österreich); PA = Sammlung Paladilhe, Faculté des 
Sciences, Montpellier (Frankreich) und SMF = Natur-Museum und Forschungs-Institut 
Senckenberg, Frankfurt am Main (Deutschland). 

Den Herren Dr. E. Binder (Genève), H. Chevallier (Paris), G. Falkner (München), 
F. Geissert (Sessenheim), E. Gittenberger (Leiden), Prof. Dr. R. Legendre (Mont- 
pellier), Dr. O. Paget (Wien) und Dr. A. Zilch (Frankfurt am Main) danke ich für die 
grosszügige Unterstützung mit Material und Informationen, Herrn F. Geissert darüber 
hinaus für das Résumé. 

RESUME 



L'espèce-type du genre Bythinella, Bulimus viridis, ainsi que les quatre Proso- 
branches pyrguloides d'Europe occidentale (Hydrobia carinulata, P aludine lia darr ieuxii, 
Paludina bicarinata et Pyrgula pyrenaica) ont été identifiés au moyen de syntypes et 
de topotypes. H en résulte que H. carinulata, P. darrieuxii et P. bicarinata sont à 
considérer comme représentants du genre Bythinella s. str. La position systé- 
matique de P. pyrenaica au sein du genre Bythinella reste indécise. 

La preuve a pu être apportée que Paludina insubrica appartient au genre Marstoniop- 
sis (Boeters 1968: 755). 

Le nombre des lamelles branchiales est plus élevé chez les o. ç de Marstoniopsis 
que chez celles de Bythinella. L'on peut distinguer les ç ç et les cfcfaussi bien des 



284 PROC. FOURTH EUROP. MALAC. CONGR. 

Bythinella que des Marstoniopsis par l'étude du par cours intestinal, sans avoir recours 
à la destruction de la coquille. 

Des syntypes de Paludina abbreviata ont été trouvés; le mode de leur test ressemble 
à celui des Marstoniopsis. L'identification de P. abbreviata reste encore problé- 
matique. 

LITERATUR 

ALTENA, С. О. VAN REGTEREN, 1936, Remarks on the generic position of Hydrobia 

steinii von Martens and Paludestrina taylori E. A. Smith with the description of 

a new genus. Basteria, 1: 64-73. 
ALZONA, C. & ALZONA BISACCHI, J., 1939, Malacof auna itálica, 1: 129-152. Genova, 

Quinto Al Mare. 
ASTRE, G., 1921, La série de types conchyliologiques établie par l'abbé Dupuy pour 

le Muséum de Toulouse. Bull. Soc. Hist, natur. Toulouse, 49: 251-263. 
BENTHEM JUTTING, T. van, 1933, Mollusca, 1 A, Gastropoda, Prosobranchia et 

Pulmonata, 7. Aufl., Leiden, A. W. Sijthoff's U-versmij N. V. 
BOETERS, H. D., 1968, Die Hydrobiidae Badens, der Schweiz und der benachbarten 

französischen Departements. Mitt. bad. Lándesver. Naturk., NF 9: 755-778. 
BOETERS, H. D., 1970, Die Gattung Microna Clessin, 1890. Arch. Molluskenk., 100: 

113-145. 
BOURDIER, F., 1942, Essai de chronologie du quaternaire moyen et supérieur. С. г. 

hebd. Séanc. Acad. Sei., Paris, 215: 473-475. 
BREGENZER, A., 1915, Anatomie und Histologie von Bythinella dunkeri. Zool. 

Jahrb., (Anat.), 39: 236-292. 
CAZIOT, E., 1907, Catalogue des mollusques terrestres et fluviátiles du département 

de l'Yonne. Bull. Soc. Sei. Hist, natur. Yonne, 60(1906): 193-277. 
Census of the distribution of british non-marine mollusca, 1951. J. Conchol., 23: 

171. 
CLESSIN, S., 1884, Deutsche Excursions-Mollusken-Fauna, 2. Aufl., 3: 321-480. 

Nürnberg, Bauer & Raspe. 
COLLOT, L., 1911, Limaeides et Helicides des Faluns de Touraine. Feuille jeun. 

Nat., (5)41: 93-99. 
DANCE, S. P., 1966, Shell collecting. London, Faber & Faber. 
DROUET, H., 1868, Mollusques terrestres et fluviátiles de la Côte-d'Or. Mem. Acad. 

imp. Sei. Arts Dijon, (Sei.), (2) 14(1866/67): 33-154. 
DUPUY, D., 1851, Histoire naturelle des mollusques terrestres et d'eau douce qui 

vivent en France, 5: 459-594. Paris, V. Masson. 
ELLIS, A. E., 1969, British snails. Reprint, London, Oxford University Press, 298 S. 
FISCHER, P., 1880, Faune malacologique de la vallée du Mont Dore. J. Conchyliol., 

Paris, 28: 289-299. 
FISCHER, P., 1885, Contribution à la faune malacologique du Puy-de-Dôme. J. 

Conchyliol., Paris, 33: 302-309. 
FORCART, L., 1959, Taxiono mische Revision paläarktischer Zonitinae. Arch. 

Molluskenk., 88: 7-34. 
FRETTER, V. & GRAHAM, A., 1962, British prosobranch molluscs. Ray Soc, 

Lond., 144: 1-755. 
GASCHOTT, O., 1931, Bemerkungen über einige Mollusken der Südalpenseen. Arch. 

Molluskenk., 63: 28-39. 
GERMAIN, L., 1931, Mollusques terrestres et fluviátiles, 2: 479-897. Paris, P. 

Lechevalier. 
GRANGER, A., 1897, Faune conchy liologique terrestre et fluviatile de la région du 



BOETERS 285 

sud-ouest. Act. Soc. linn. Bordeaux, 52: 237-271. 
IMHOF, O. E., 1901, Wassermolluskenfauna der Schweiz, insbesondere der Seen. 

Biol. Zentralbl., 21: 43-62. 
JACKSON, J. W. & TAYLOR, F., 1904, Observations on the habits and reproduction of 

Paludestrina taylori. J. Conchol., 11: 9-11. 
JAECKEL, S. G. A., 1962, Ergänzungen und Berichtigungen zum rezenten und quartären 

Vorkommen der mitteleuropäischen Mollusken, S 25-279. Leipzig, Quelle & 

Meyer. 
JAECKEL, S. G. A., 1967, In: J. lilies, Limnofauna europaea. S 89-104, Stuttgart, 

G. Fischer. 
JAECKEL, S. H., KLEMM, W. & MEISE, W., 1958, Die Land- und Süsswasser- 

Mollusken der nördlichen Balkanhalbinsel. Abh. Ber. stl. Mus. Tierk. Dresden, 

23: 141-205. 
J0HANSEN, A. C, 1918, Randers Fjords Naturhistorie, 5G: 393-444. Kobenhavn, 

C. A. Reitzel. 
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Bythinella dunkeri Frauenfeld, Giessen, Dissertation, 84 S. 
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76 S. 



MALACOLOGIA, 1973, 14: 287-289 

PROC. FOURTH EUROP. MA LAC. CONGR. 

ELECTROPHORESIS AS A SUPPORT FOR THE IDENTIFICATION 
OF VARIOUS AFRICAN BIOMPHALARIA 

Gudrun Wium-Andersen 

Danish Bilharziasis Laboratory, Charlottenlund, Denmark 

ABSTRACT 

Esterases from the hepato-pancreas of African Biomphalaria spp. have been 
examined by means of starch-gel electrophoresis. On the basis of esterases it 
was possible to separate the following species determined from their morpho- 
logical characters: B. pfeifferi (Krauss), B. alexandrina (Ehrenberg), В. 
camerunensis (Boettger) and B. sudanica tanganyicensis (Smith). B. alexan- 
drina wansoni Mandahl- Barth is identical with B. camerunensis in regard to the 
esterase pattern. 

The esterases emphasize the conformity found in shell morphology between 
Biomphalaria alexandrina from Ismailiya and B. sudanica tanganyicensis . In 
B. alexandrina esterases varied from one population to another, while they were 
completely constant in all B. pfeifferi populations examined. This variability 
parallels a great variation in susceptibility to infection with Schistosoma man- 
soni (Sambon) found in the populations of B. alexandrina examined, and a con- 
stant susceptibility to infection with S. mansoni in the populations of B. pfeifferi 
examined. 

It is a well known fact that species of the genus Biomphalaria act as intermediate 
hosts of Schistosoma mansoni, which causes the intestinal form of human bilharziasis. 

Some of the African species of Biomphalaria show great variation in shell morpho- 
logy as well as in anatomy, which impedes the classification of the species. As a 
supplement to the morphological characters I have used biochemical methods. In the 
beginning I have examined esterases from the hepato-pancreas by using starch-gel 
electrophoresis for the purpose of achieving a better understanding of the taxonomy 
within the genus and also hoping to get some information as to whether the differences 
in susceptibility within a certain species can be correlated to different infraspecific 
forms. 

Fig. 1 shows the sample localities: Biomphalaria alexandrina from 8 localities, 
B. pfeifferi from 4 localities, B. camerunensis from 4 localities near Kinshasa in 
Congo, B. alexandrina wansoni from 2 localities near Kisangani and B. sudanica 
tanganyicensis from Mwanza in Tanzania. Fig. 2 shows a diagram of the esterase 
bands found in the examined Biomphalaria species. In B. pfeifferi I have found 6 
esterase bands, 2 of which move towards the cathode and the remaining towards the 
anode. The maximum number of esterase bands found in B. alexandrina was 11. 
However, with this technique B. alexandrina from Ismailiya did not show the same bands 
in the B-series, but instead 2 more powerful ones with a quite thin band in between 
moving a little faster towards the anode. These 3 bands are almost confluent. In all 
other B. alexandrina populations B lf B 2 , and B 3 were always present. In B. camerun- 
ensis the technique shows 8 esterase bands. B. alexandrina wansoni is identical with 
B. camerunensis. Unfortunately there was only a limited number of specimens of B. 
sudanica tanganyicensis at my disposal, but the examined specimens show bands in 
the B-series identical with those of B. alexandrina from Ismailiya. 

I have found that the populations of Biomphalaria pfeifferi from Ethiopia, Katanga 
and Uganda are identical and all bands appear with a frequency of 100%. The Rhodesia 



(287) 



288 



PROC. FOURTH EUROP. MALAC. CONGR. 



Na 



II 



B. pfeifferi 



B. alexandrina 
(Abu Rawaash) 



B. alexandrina 
(Alexandria) 



B. alexandrina 
(Qalyub) 



B. alexandrina 

(Suez) H 



II 



В. alexandrina 
(¡s maili у a) 



В. sudanica 



В. camerunensis 



В. alex. wansoni- 
B. camerunensis 



II 



If 



ь 



Ni 



Ni 



Il II 

III llll 

III II 
III III 
III II 
III II 
llll I 
III III 
III III 



u> CD 



О 



FIG. 1. Collecting localities for the examined African Biomphalaria. 

population was similar to the 3 mentioned, apart from the lacking band A 1# 

The variation in the esterase pattern in Biomphalaria alexandrina is very great 
from one population to another. The Ismailiya population can always be distinguished 
from the others by the presence of C^. All B. camerunensis populations examined are 
identical and they do not differ from the B. alexandrina wansoni populations. 

The esterases suggest that the 3 species Biomphalaria pfeifferi, B. sudanica 
tanganyicensis and B. camerunensis identified on morphological characters are well 
established species, as they have different esterases, as opposed to B. alexandrina, in 
which the variability makes the state less clear. 

Different populations of Biomphalaria alexandrina vary in their susceptibility to 
Schistosoma mansoni from Egypt and elsewhere, whereas populations of B. pfeifferi 
from geographically widely separated localities all have the same high susceptibility 
to all strains of S. mansoni. 

The results obtained demonstrate a correlation between uniform esterase pattern 
and high susceptibility of Biomphalaria pfeifferi, whereas in B. alexandrina there is a 



WIUM-ANDERSEN 



289 




# Biomphalaria alexandrina 

▲ /77777 — •• — pfeifferi 

^ — — '. — alex.wansoni 

ф — " — camerunensis 

■ — •< — sudani ca 



FIG. 2. The esterase bands found in African Biomphalaria. 

great variation both in the esterase pattern and in the susceptibility to Schistosoma 
mansoni. These results are remarkable considering the much wider geographical 
distance between the B. pfeifferi localities than between those of the B. alexandrina 
populations. 

The Biomphalaria alexandrina population from Ismailiya resembles B. sudanica 
in shell shape, length of central teeth and in the esterase pattern. Now the question 
arises whether this population should be considered as an isolated population of B. 
sudanica. Perhaps the peculiar distribution of B. alexandrina, its variation in sus- 
ceptibility, the unstable morphological characters and the esterases suggest that B. 
alexandrina should rather be regarded as a hybrid between B. pfeifferi and B. sudanica. 
In any case, the great variation in B. alexandrina indicates that this species is most 
probably a species in evolution. 

In morphological characters Biomphalaria alexandrina wansoni is closely related 
to B. camerunensis and they have identical esterases. I think that B. wansoni must 
be regarded as an inland form of B. camerunensis and not as a subspecies of B. 
alexandrina. 



MALACOLOGIA, 1973, 14: 291-301 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE MINUTE SHELL STRUCTURE OF THE GLOCHIDIUM OF SOME SPECIES OF 
THE GENERA UNIO, POTOMIDA AND ANODONTA (BIVALVIA, UNIONACEA) 

Folco Giusti 

Institute of Zoology, Siena, Italy 

INTRODUCTION 

Anyone who has read or even leafed through texts on Unionacea systematics will 
easily understand the reason for this research which I have undertaken. In fact, the 
systematics of this group of molluscs is in chaos, particularly at the level of species. 
This systematic disorder is caused principally by the fact that the Unionacea, like 
most bivalves, do not possess a structure which gives valid characteristics so that 
the different species may be classified with any certainty. The only structure useful 
for classification, the shell, is in fact very variable, as it is subject to environmental 
factors, and so does not lend itself to a sure identification. In the past, exactly as has 
happened in all the other groups of molluscs, the study of the shells only has led to 
the creation of an incredible number of species, with the result that, if the place 
where they were taken is not considered, it is practically impossible to distinguish 
one species from another. Thus my attention was drawn to young bivalves, and in 
particular to those larval forms known everywhere as "glochidia." It seemed logical 
that larval forms which are highly differentiated, as in the glochidium, possessing as 
they do a small rather complicated embryo shell, would provide on further study 
characteristics useful not only for testing the validity of the classification of the dif- 
ferent species, but also for the clarification of the interrelations between the different 
genera. 

The shell and the attachment structures of the glochidium of Unio. 

My research began with a study of the glochidium of a population of Unio living on 
the outskirts of Pavia. According to Zilch (1967), the species should be U. elongatulus 
glaucinus Porro, but in the past it has at times been called U. requieni and at other 
times U. pictorum or U. athesinus. 

The shell of the glochidium is made of 2 triangular valves, the mirror image of 
each other, held together by a ligament (Fig. 1). Under the scanning electron micro- 
scope at low magnification it is already possible to make out that the outer surface 
of the 2 valves is not smooth, but covered with numerous evenly-distributed protu- 
berances (Figs. 2 and 4). In many places the valve surface is furrowed as well with 
numerous small hollows (Figs. 3 and 4). Finally, on examining fragments of valves, 
it is possible to make out that the shell is made of 2 parts. One is external, like a 
thin skin, with the above described protuberances on the outside, and one is internal, 
of a crystalline aspect, full of numerous holes (Figs. 2 and 3). The hollows noticed 
on the surface of the valves originate in the furrowing of the external skin following 
the holes of the crystalline layer. In both valves, the attachment structure is situated 
on the anterior apex and is made up of a margin possessing numerous pointed spines 
(Figs. 8 and 9). Closing the valves the margins fold towards the inside, fastening the 
spines firmly into the tissues of the host fish (Figs. 10 and 11). The apex of each 
valve, all around the spiny margin, has small very dense spines for a short stretch 
(Fig. 11). 



(291) 



292 PROC. FOURTH EUROP. MALAC. CONGR. 

The shell and the attachment structures of the glochidium of Potomida. 

The research was carried out on the larval forms of Potomida littoralis littoralis 
(Lamarck) from the river Ebro, Spain 1 . In this species which, according to Zilch 
(1967) belongs to the subfamily Quadrulinae of the Unionidae, there has been found a 
particular kind of glochidium. Its shell in fact has an hemispherical shape and lacks 
a spiny margin like that seen in Unio. There are only small spines distributed all 
along the edge of the 2 valves (Fig. 12). On the other hand the sculpture of the external 
surface of the valves strongly resembles that seen in Unio (Fig. 6). The external 
protuberances, as seen in Unio (Fig. 5), completely cover the smallest spines of the 
attachment edge (Fig. 7). 

The shell and the attachment structures of the glochidium of Anodonta. 

My research on the glochidium of Anodonta was carried out on materials coming 
from 2 different distant populations of Anodonta, the one from Lake Maggiore and the 
other from Lake Trasimeno (Italy). Nowadays these 2 populations, distinguished in 
the past by many different names, should be considered as belonging to 1 single species, 
Anodonta cygnea (Linnaeus) according to Zilch (1967). The shell of the glochidium of 
Anodonta, even if of greater size (about 300 ¡j. long), appears as in Unio, in a triangular 
shape with 2 valves of equal size, held together by a ligament (Fig. 13). In this case, 
too, the external surface of the valves is not smooth, both the glochidium of the 2 
different populations having numerous hairy excrescences. These are very thick near 
the base of the shell (Fig. 15), but they become more and more rare towards the 
central part of the valve where they are found in parallel rows (Figs. 14 and 16). Near 
the anterior apex of the shell the protuberances described are even rarer and less 
obvious. 

As seen in Unio, the shells of the glochidium of Anodonta are also found to consist of 
2 parts, one external, a very thin layer, the other internal, much thicker and of crystal- 
line aspect (Figs. 17 and 19). There are many holes in the latter (Figs. 18 and 19). 
The numerous hollows which are seen on the outer surface of the valves (Figs. 13, 14 
and 16) originate in the wrinkling of the external layer over the holes in the crystalline 
layer. The attachment structure of the glochidium of Anodonta is made in the same 
way in the 2 populations I examined, but Anodonta has certain characteristics which 
differ from those described in Unio. On each valve they consist of an apical margin 
that is covered with long pointed spines (Figs. 20, 23, 24, 25 and 26). There are 
fewer spines than in Unio, both at the base of the spiny margin and on the spiny mar- 
gin itself (Figs. 21 and 22). 

CONCLUSIONS 

Besides giving simple information concerning the morphology of the shell and the 
attachment structure of the valves of the glochidium I examined, I belive I have also 
shown their importance. The material I examined is too scant to give any practical 
result, but the field is open, and with the help of European malacologists and others 
from the rest of the world, I hope to be able to examine other materials and so begin 
a comparison of the data obtained and attempt making use of these in a revision of the 
classification of Unionidae. 



*Му sincere thanks to Dr. Adolf Zilch from Frankfurt, who sent me the material. 



GIUSTI 293 

SUMMARY 

The shell and the attachment structure of the glochidia of some species belonging 
to the genera Unio, Potomida and Anodonta have been examined with the scanning 
electron microscope. The author points out that the number and disposition of the 
attachment spines and the external sculpture of the surface of the shell seem to offer 
sufficient characteristics to be used in the systematical study of these bivalves. 

REFERENCES 

BOURGUIGNAT, J. R., 1883, Aperçu sur les Unionidae de la péninsule italique, p 1- 
117. Tremblay, Paris. 

BRODNIEWICZ, I., 1968, On glochidia of the genera Unió and Anodonta from the 
quaternary fresh-water sediments of Poland. Acta palaeont. Pol., 13(4): 619-630. 

HAAS, F., 1940, A tentative classification of the palearctic Unionids. Pubis. Field 
Mus., Zool. Ser., 24(2): 115-141. 

ZILCH, A., 1967, Die Typen und Typoide des Natur-Museum Senckenberg, 39. Mol- 
lusca, Unionacea. Arch. Molluskenk., 97(l/6): 45-154. 



294 PROC. FOURTH EUROP. MALAC. CONGR. 



FIG. 1. The shell of the glochidium of Unio elongatulus glaucinus. The ligament (L) holding 
together the 2 valves (V). 7 2 Ox. 

FIG. 2« The shell of the glochidium of Unio elongatulus glaucinus. In this fragment it is possi- 
ble to see the external part of the shell like a thin skin (E) and the internal one of crystalline 
aspect (I). 3,000x. 

FIG. 3. The shell of the glochidium of Unio elongatulus glaucinus. Fragment showing 2 of the 
holes of the internal crystalline layer externally closed by the "thin skin" like layer. 10,000x. 

FIG. 4. The shell of the glochidium of Unio elongatulus glaucinus. The outer surface of the 
"thin skin" layer is covered with numerous little protuberances. The hollows (H) on the surface 
originate in the furrowing of the "thin skin" following the holes of the crystalline layer. lO.OOOx. 

FIG. 5. The shell of the glochidium of Unio elongatulus glaucinus . The "thin skin" layer is 
extended to completely cover the smallest spines of the attachment structure. lO.OOOx. 

FIG. 6. The shell of the glochidium of Potomida littoralis littoralis. The outer surface of the 
shell is covered with numerous little protuberances. 16,000x. 

FIG. 7. The shell of the glochidium of Potomida littoralis littoralis. The external little pro- 
turberances completely cover the spines of the attachment edge. 16,000x. 



GIUSTI 



295 




kl . %yé 





296 PROC. FOURTH EUROP. MALAC. CONGR. 



FIG. 8. The attachment structure of the glochidium of Unio elongatulus glaucinus. On the ante- 
rior apex of a valve there is the initial portion of the attachment structure possessing numerous 
pointed spines. 3,000x. 

FIG. 9. The attachment structure of the glochidium of Unio elongatulus glaucinus. The initial 
portion of the attachment structure of the 2 valves of a glochidium. 1, 350x. 

FIG. 10. The attachment structure of the glochidium of Unio elongatulus glaucinus. Side view 
showing the spiny margin of the attachment structure folded towards the inside of the valve cavity. 
l,000x. 

FIG. 11. The attachment structure of the glochidium of Unio elongatulus glaucinus. The spiny 
margin with numerous rows of spines. 2, OOOx. 

FIG. 12. The attachment edge of the glochidium of Potomida littoralis littoralis. The spiny struc- 
ture is lacking; numerous small spines are distributed all along the edge of the valves. 1, OOOx. 



GIUSTI 



297 




298 PROC. FOURTH EUROP. MALAC. CONGR. 



FIG. 13. The shell of the glochidium of Anodonta cygnea from Lake Trasimeno (Italy). 230x. 

FIG. 14. The shell of the glochidium of Anodonta cygnea from Lake Trasimeno (Italy). The 
outer surface of the "thin skin" layer has, in the central part of the valves, numerous hairy ex- 
crescences in parallel rows. The hollows originate in the wrinkling of the external "thin skin" 
layer over the holes of the internal crystalline one. 10, OOOx. 

FIG. 15. The shell of the glochidium of Anodonta cygnea from Lake Trasimeno (Italy). Near the 
base of the shell the hairy excrescences are very thick. 15, OOOx. 

FIG. 16. The shell of the glochidium of Anodonta cygnea from Lake Maggiore (Italy). The hairy 
excrescences have the same shape and disposition as those seen on the outer surface of the "thin 
skin" layer of the glochidium of A. cygnea from Lake Trasimeno (Italy). 10, OOOx. 

FIG. 17. The shell of the glochidium oí Anodonta cygnea. In this fragment it is possible to see 
the 2 layers constituting the valves; the external one like a "thin skin" (E) and the internal one of 
crystalline aspect (I). 10, OOOx. 

FIG. 18. The shell of the glochidium of Anodonta cygnea. Numerous holes are in the internal 
crystalline layer of the valves. l,700x. 

FIG. 19. The shell of the glochidium of Anodonta cygnea. The internal crystalline layer of the 
valves (I) of the glochidium is still present in the initial portion of the shell (S) of a young Ano- 
donta. 3,000x. 



GIUSTI 



299 




300 PROC. FOURTH EUROP. MALAC. CONGR. 



FIG, 20. The attachment structure of the glochidium of Anodonta cygnea. On the anterior apex 
of a valve there is the initial portion of the attachment structure. The spines are fewer than in 
Unto. 2,600x. 

FIG. 21. The attachment structure of the glochidium of Anodonta cygnea. The spiny margin is 
folded towards the inside of the valve cavity. 870x. 

FIG. 22. The attachment structure of the glochidium of Anodonta cygnea. Few spines are on the 
spiny margin. 1 , 500x. 

FIG. 23. The attachment structure of the glochidium of Anodonta cygnea from Lake Maggiore 
(Italy). The initial portion. 1 , OOOx. 

FIG. 24. The attachment structure of the glochidium of Anodonta cygnea from Lake Trasimeno 
(Italy). The initial portion. 1 , OOOx. 

FIG. 25. The attachment structure of the glochidium of Anodonta cygnea from Lake Maggiore 
(Italy). The initial portion. 1 , OOOx. 

FIG. 26. The attachment structure of the glochidium of Anodonta cygnea from Lake Trasimeno 
(Italy). The initial portion. 1 , OOOx. 



GIUSTI 



301 




MALACOLOGIA, 1973, 14: 303-312 

PROC. FOURTH EUROP. MALAC. CONGR. 

SPECIES ISOLATION IN SYMPATRIC POPULATIONS OF THE 

GENUS DIPLOMMATINA (GASTROPODA, PROSOBRANCHIA, 

CYCLOPHORIDAE, DIPLOMMATININAE) 

John F. Peake 

British Museum (Natural History), London, England 

ABSTRACT 

A study of sympatric populations of Diplommatina species in Malaya and the 
Solomon Islands indicates that the distribution of the morphological features 
exhibited by these taxa can be interpreted in terms of maintaining or reflecting 
species isolation, both genetical and ecological. The morphological characters 
considered are shell size, direction of coiling and shell shape. Selection or 
competitive exclusion favors divergence of these features amongst coexisting 
populations. 

Examples of sympatric populations of closely-related species of snails and slugs 
are numerous, indeed, the molluscan faunas of many isolated islands can be charac- 
terised by this phenomenon. These faunas could have arisen through autochthonous 
evolution from a few initial propagules or by multiple colonisations of a number of 
closely-related taxa each possessing high probabilities for successful dispersal. 
Studies of island faunas thus provide abundant opportunities for investigating the 
strategems involved in maintaining species isolation, both genetical and ecological. 
Yet with a few exceptions there have been remarkably few attempts to analyse the 
evolution or the distribution of sympatric populations of non-marine molluscs in such 
terms. 

The molluscan fauna of a series of isolated limestone hills in Malaya exhibit a pattern 
typical of island faunas. A number of genera are represented by groups of closely- 
related species. Purchon & Solari (1968) have suggested that the occurrences of these 
taxa show a random pattern, as the number of species recorded for each hill fit a 
Poisson distribution, this type of pattern resulting from the interaction of a number of 
random variables. The purpose of this paper is to analyse the distribution of one of 
the genera, Diplommatina, that occurs on these limestone hills and to amplify the 
study by including data from another area, the Solomon Islands. It will be suggested 
that the results can only be interpreted satisfactorily in terms of interactions be- 
tween sympatric populations and that this factor is important in determining the dis- 
tribution patterns of the taxa included in the genus. 

Groups of sympatric species occur throughout the range of the genus Diplommatina, 
from India in the west to Samoa in the east. These small prosobranch snails exhibit 
a number of diverse shell forms and it is the distribution of these morphological 
forms that provides a means of demonstrating interactions between coexisting popu- 
lations. A number of subgenera have been recognised on the basis of these differences 
in shell morphology and the genus has been separated from the closely -related taxon 
Palaina on the presence or absence of a parietal denticle in the aperture of the shell. 
The taxonomic status of these groups is open to doubt and for that reason within the 
context of this paper all the species are referred to a single genus Diplommatina 
sensu latu. 

Detailed information is available for populations of Diplommatina species from only 

(303) 



304 



PROC. FOURTH EUROP. MALAC. CONGR. 




FIG. 1. Species of Diplommatina from the Solomon Islands, figures to illustrate diversity of 
shell form; as no specific epithets are available (see text) shells are identified by locality. 1, 
Nuhu, Guadalcanal; 2, Nuhu, Guadalcanal; 3, 12 kilometres south of Wainoni, San Cristobal; 
4, Mount Austen, near Honiara, Guadalcanal; 5, Mount Austen, near Honiara, Guadalcanal; 6, 
Nuhu, Guadalcanal; 7, 12 kilometres south of Wainoni, San Cristobal; 8, Mount Austen, near 
Honiara, Guadalcanal (apertural and lateral views); 9, 20 kilometres south of Wainoni, San 
Cristobal (apertural and lateral views). 



2 areas, the Solomon Islands and Malaya. The data for the Solomon Islands are based 
on collections made by the author while a member of a Royal Society expedition (June 
to December 1965) and by Dr. P. J. M. Greenslade during his tenure in the local 
Department of Agriculture. All the collections were made in rainforest (Peake, 1967, 
1968). The majority of specimens were found in leaf litter either in gullies, between 
the buttresses of tree trunks or in small clefts and ledges on steep slopes. Records 
from other habitats include arboreal sites, for example, the basal leaf rosettes of both 
Pandanus and Asplenium plants. No distinction could be detected between the species 
composition of the molluscan faunas existing on different geological formations. In 
contrast, the data for Diplommatina in Malaya refers to faunas from precipitous 



PEAKE 



305 



TABLE 1. Distribution of Diplommatina species in the Solomon Islands; only samples containing 
more than a single species included. Distribution scored as representation of 
dextral (D) or sinistral (S) forms in different size classes (see text for reasons). 
Species with overlapping size parameters joined by vertical boxes. 



Island 


Locality 


Size class 


1 


2 


3 


4 


Guadalcanal 


Mount Austen 


D 




D 

S 




s 


D 




Nuhu 


D 




D 

S 




D 






Tambulusu 




S 






San Cristobal 


Huni River 




s 


D 






2 km East of Huni River 




s 


D 






Ultrabasics near Wainoni 


S 


s 


D 


D 




12 km South of Wainoni, Camp Site 


S 




D 

S 




D 


D 




80 m altitude 


S 






D 

S 




D 




240 m altitude 


s 


D 








400 m altitude 


s 




D 






20 km South of Wainoni 
East side of river 


s 






D 

S 








West side of river 


s 


D 




D 

S 






Malaita 


Maramiske 


s 




D 




Santa Ysabel 


Fulkora Point 




S 


s 




Chois eul 


Wagino 


s 


s 







limestone hills; records for other habitats being extremely rare and then only from 
localities at high altitudes (Laidlaw, 1949; Peake unpubl.). In this context the hills 
are considered as islands of almost bare rock and comparatively sparse vegetation 
isolated by alluvial deposits which often support forest vegetation (Tweedie, 1961). 
Information for Malaya is based on the published records of Laidlaw (1949), Tweedie 
(1961), Benthem Jutting (1960) and Berry (1965), supplemented with occasional infor- 
mation from museum collections. 

For each population shell size is indicated by the simple measurements of maximum 
height and breadth, while shell shape is scored for direction of coiling and shell form. 
An indication of the diversity of shapes (Figs. 1 and 2) is provided by a very simple 
classification. The direction of coiling, whether dextral or sinistral, is constant for 
species in samples from the Solomon Islands, but Tweedie (1961) has recorded from 
Malaya a few sinistral individuals amongst predominately dextral populations, although 
the converse has not been observed. 



306 PROC. FOURTH EUROP. MALAC. CONGR. 

SOLOMON ISLANDS 

Specimens of Diplommatina were collected on 11 islands in the archipelago, but 
samples containing more than a single species were obtained from only 5 (see Table 1). 
The systematics and nomenclature of these taxa have not been finalised and, therefore, 
in this paper specific epiphets have not been given (see Fig. 1). Samples with the 
highest diversity of species were always associated with the thickest and more stable 
deposits of litter and in such habitats a maximum of 5 species were found coexisting. 
Within these collections up to 4 distinct size classes are recognizable in any single 
sample, although usually a smaller number are represented. These groups are iden- 
tified on the basis of shell height and breadth (see Figs. 3 and 4). They are clearly 
defined and, typically, no overlap between adjacent groups has been discovered, even 
though the constituent species may vary. 

Occasionally, however, the size parameters for 2 species are superimposed or 
overlap to form a single group or unit, but again the isolation of the size classes from 
adjacent groups is maintained. In those instances where the parameters for size 
overlap, there is always clear morphological separation of the species on the basis 
of shell shape. At the simplest level this consists of one species being dextral, the 
other sinistral. 

MALAYA 

A similar empirical relationship of shell size and shape is exhibited by populations 
from the limestone hills in Malaya; the data are summarised in Table 2. A limitation 
has been imposed by the utilisation of a variety of sources for this information. Thus 
shell height is the only parameter used to indicate shell size and often there is only a 
single measurement available. For the latter the criteria for deciding potential 
range of each size class, and therefore overlap, are based on extrapolation from the 
data for the Solomon Islands. It is impossible to distinguish populations which are 
truly coexisting in time or space; they can only be described as being found together 
on a particular hill. This is probably not a serious limitation and many of the hills 
are quite small. In a few instances the published records for closely adjacent hills 
have been amalgamated. Even with these restrictions the data are sufficient to cor- 
roborate the results from the Solomon Islands and permit the analysis to be extended. 

Information is available for 28 localities and these provide evidence for a maximum 
of 5 species coexisting and being divided into 4 size classes. There are 6 examples 
of 2 species with the parameters for size being superimposed or overlapping; in each 
case one species is dextral, the other sinistral. Amongst these pairs there is further 
evidence of morphological divergence. The shell of all the dextral species conform to 
2 rather similar shapes (see Fig. 2, types 1 and 2), while many of the sinistral taxa 
deviate from these patterns and have a different and indeed rather bizarre form (Fig. 
2, type 3). This contrast is emphasised by comparing 2 groups of sinistral species, 
those overlapping and those not overlapping on the size classes of dextral taxa. The 
former (4 species) includes all the morphological forms of type 3, while the latter 
(3 species) approach closer to the form of the dextral species types 1 and 2. Thus 
differences in direction of coiling appear to be reinforced by divergence in shell 
shape. 

The only possible exceptions to the correlation between shell size and direction of 
coiling are provided by the records of 2 dextral species coexisting; these are Diplom- 
matina nevilli and D. streptophora on hill number 10 and D. nevilli and D. ventriculus 
on hill number 6 (see Table 2). D. nevilli exhibits the widest size range recorded for 
any species found in Malaya, while D. streptophora has only been found on 2 hills. 



PEAKE 



307 




cû 




H 



cû 




H 



FIG. 2. Malayan species of the genus Diplommatina: a classification of shell shape. 



Type 

1 
2 
3 



Direction of coiling 



Dextral 

D. nevilli (1) 

D. streptophora (2) 



Sinistral 



acme (4) 
tweediei (5) 
attenuata (3) 



FIG. 3. Diagrammatic representation of the distribution of size classes in samples. H, shell 
height; B, shell breadth. Upper figure, 3 species divided into 3 size classes; Lower figure, 
5 species divided into 4 size classes; size parameters for 2 species overlapping to form a single 
group. 



The range of shell height for D. nevilli is 1.82 to 3.45 mm, but for D. streptophora 
there is only a single recorded measurement of 2.5 mm. Where the 2 coexist on hills 
6 and 10 the size of D. nevilli is at the extreme upper limit and, therefore, exhibits 
the greatest possible divergence, within the size range, from that known for the other 
species. Thus the limited data available provides no evidence that the size ranges of 
these 2 dextral species overlap. The information for D. nevilli and D. ventriculus 
from hill number 6 is also ambiguous. Measurements for D. ventriculus from that 
hill are not available and, therefore, the shell height given is extrapolated from that 



308 PROC. FOURTH EUROP. MALAC. CONGR. 

for a limited number of records. There is no reason to presume that the shell size 
of this species does not vary as does that of D. nevilli (see discussion). 

DISCUSSION 

The significance of variations in the shape of the shell of non-marine molluscs has 
frequently been questioned. Although correlations between physical factors of the 
environment and shell shape have been demonstrated by various authors (e.g., Rensch, 
1932; Gould, 1969) evidence for interactions between species influencing these features 
is limited. A notable exception has been the studies on Partula by Clarke & Murray 
(1969). 

In this study an empirical relationship has been demonstrated for the distribution 
patterns exhibited by the different morphological forms of Diplommatina. Shells of 
coexisting populations are separated by size and shape, the latter being direction of 
coiling and shell form. In the few species that have been dissected it is obvious that 
these variations are not correlated with differences between the sexes. Confirmation 
is provided by the observation that many taxa have been found either isolated as single 
populations or not consistently associated with other forms. Morphologically similar 
populations have not been found coexisting. It must, therefore, be concluded that either 
competitive exclusion is operating for such species or natural selection favours diver- 
gence subsequent to initial colonisation. The outcome after initial colonisation is 
probably not predictable and both could occur on different occasions or in distinct 
areas of the species range. Moreover there is no evidence that dispersal is a limiting 
factor to the distribution of, at least, some species of Diplommatina; the small size of 
these snails must increase the probability of successful dispersal and colonisation 
(Peake, 1969). 

Size also varies under different physical regimes. Records of a single species from 1 
island in the Solomon Islands, where there is no other species of Diplommatina, demon- 
strates that size decreases with increasing altitude. The magnitude of this variation is 
not equivalent, however, to the difference between the means of size classes recorded 
from other islands in the archipelago. This variation is consistent with the correlation 
demonstrated by Berry (1963) for differences in shell size of D. nevilli and annual 
rainfall in the different areas. The height of the shells was shorter in areas where the 
annual rainfall was highest. In the Solomon Islands an increase in altitude would be 
associated with an increase in the wetness of the environment. This comparison 
illustrates a distinction between the climates of the 2 regions; the Solomon Islands 
can be described as continuous wet, while that for Malaya shows wide variations with 
many areas being described as seasonally wet or with irregular periods of drought 
(Peake, 1968). Therefore, it may be postulated that variations in shell size attribu- 
table to differences in climate would be greatest in Malaya compared with the Solomon 
Islands. This appears to be true for comparisons between D. nevilli and taxa from the 
Solomons, but whether it applies to other species from Malaya is unknown. For 
populations of Diplommatina from Malaya the variation in shell size with climate makes 
the interpretation of shell morphology in relation to other factors more complex. In 
the Solomon Islands, however, where the climate is more constant this type of variation 
is not so important. 

The differences in shell size and shape exhibited by populations of Diplommatina 
from the Solomon Islands are interpreted in terms of promoting species isolation, 
both ecological and genetical. The distribution of species in Malaya supports such 
an hypothesis, but with an additional complication produced by variation of shell size 
with differences in climate. The relative importance of the morphological features in 
maintaining, reflecting or reinforcing isolation cannot be determined without more 



PEAKE 



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ecological information and breeding experiments. However, the patterns shown by 
these variations in shell morphology demonstrate the selective advantages of such 
differences. Further evidence for selection is provided by comparing the distances 
separating adjacent size classes in samples from the Solomon Islands. Where the 
direction of coiling is the same for adjacent groups the distances tend to be greater 
than for adjacent groups where the direction of coiling is different (see Fig. 4). 
Selection favours greater divergence of size in populations with convergence of other 
morphological features. 

It can be postulated that the presence of morphological differences between the 
species, for example size, could lead to differentiation in the ecological niches 
occupied; niche is used here in Hutchinson's sense (1965). Populations of such species 
could coexist without spatial separation, as they could utilise different resources or 
elements of the environment. Hutchinson (1965) has indicated that differences in size 
of the order of 130:100 would be sufficient to allow different proportions of the avail- 
able food supply to be taken. The differences between the mean points of the size clas- 
ses of Diplommatina are of this order and in many cases greater when comparisons 
are made between populations with shells having the same direction of coiling. How- 
ever, this relationship does not hold for populations with different direction of coiling. 
If the differences between size classes reflect variations in the niches occupied, are 
the morphological features associated with similar ecological disparity? 

Ecological information for Diplommatina is limited. The structure of the radula 
indicates that all the species belong to a similar feeding type; they are probably all 
grazers. In the Solomon Islands the disjunct and very limited distributions displayed 
by many species suggest specialised ecological requirements, but this type of in- 
formation is not conclusive. Differential dispersal of snails in the litter, during 
torrential rainstorms, might give rise to such a pattern (Peake 1968). Observations 
on a species of a related genus Opisthostoma (Berry 1962) indicated that the distances 
between the small, but numerous, varices on the shell each represent a single day's 
growth. Species of Diplommatina exhibit differences in this feature and, therefore, it 
is presumed differences in the growth patterns and life cycles. The possibility of 
predators acting as agents selecting different shell forms or limiting the possibilities 
of competition must not be discounted, for potential predators do exist. Ants have 
been recorded carrying small snails and on the Malayan hills there are a variety of 
carnivorous snails belonging to the pulmonate family Streptaxidae. 

It is tempting to extrapolate from data from the pulmonate genus Partula and postu- 
late that direction of coiling is important in maintaining sexual isolation. Clarke & 
Murray (1969) have demonstrated that where the distributions of 2 typically sinistral 
species overlap there is a gradual change in the population of one to become predomi- 
nately dextral and thereby reduce interbreeding. 

If the hypothesis is correct that the differences in shell morphology are important 
in maintaining isolation between species, then this isolation probably cannot be con- 
sidered as either genetical or ecological, but as a combination of both. It is possible 
to speculate further on the importance of variations in size of taxa like Diplommatina 
nevilli. Different populations of this species, although similar in shape, exhibit a wide 
divergence in size, with supposed 'dwarf forms' being recognised. Although such vari- 
ations can be correlated with climate, are these populations conspecific with variations 
in size being genetically determined and reflecting exploitation of different niches? If 
so, do they represent stages in incipient speciation? 

ACKNOWLEDGEMENTS 

The author is indebted to the Trustees of the British Museum (Natural History) and 
to the Royal Society for enabling him to participate in an expedition to the Solomon 
Islands. To G. Smith and Miss M. Elsmore thanks must be expressed for considerable 



PEAKE 



311 



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FIG. 4. Distribution of size classes in3 samples from the Solomon Islands. Open squares, dex- 
tral forms; solid circles, sinistral forms. Upper figure, 4 species illustrating none overlapping 
size classes. Sample from Ultrabasic rocks, near Wainoni, San Cristobal. Centre figure, 5 
species with the size parameters for 2 overlapping to form a single group. Sample from Mount 
Austen, near Honiara, Guadalcanal. Lower figure, 3 species with size parameters for 2 over- 
lapping to form a single group. Sample from 20 kilometres south of Wainoni, San Cristobal. 
Note: not all the specimens included in a sample are represented on these figures, but all records 
would be contained within the dotted lines. 



312 PROC. FOURTH EUROP. MALAC. CONGR. 

assistance in measuring and analysing the samples of Diplommatina. 

BIBLIOGRAPHY 

BENTHEM-JUTTING, W. S. S., 1960, Non-marine Mollusca of the limestone hills in 

Malaya. In: Proc. Cent, and Bicent. Congr. Biol., Singapore, 1958. 
BERRY, A. J., 1962, The growth of Opisthostoma (Plectostoma) retrovertens Tomlin, 

a minute cylcophorid from a Malayan limestone hill. Proc. malacol. Soc. Lond., 

35: 46-49. 
BERRY, A. J., 1963, Growth and variation of the shell in certain Malayan limestone 

hill snails. Proc. malacol. Soc. Lond., 35: 203-206. 
BERRY, A. J., 1965, A collection of land Mollusca from limestone in Ulu Kelantau. 

Bull. Natn. Mus. St. Sing., 33: 27-30. 
CLARKE, B. & MURRAY, J., 1969, Ecological genetics and speciation in land snails 

of the genus Partula. Biol. J. Linn. Soc. Lond., 1: 31-42. 
GOULD, S. J., 1969, An evolutionary microcosm: Pleistocene and Recent history of 

the land snail P. (Poecilozonites) in Bermuda. Bull. Mus. comp. Zool. Harvard 

Coll., 138: 407-531. 
HUTCHINSON, G. E., 1965, The ecological theater and the evolutionary play. Yale 

University Press, New Haven, Conn., 139 p. 
LAIDLAW, F. F., 1949, The Malayan species of Diplommatina (Cyclophoridae). Bull. 

Raffles Mus., 19: 199-215. 
PEAKE, J. F., 1967, Land molluscs of the Solomon Islands. J. anim. Ecol., 36: 68P- 

70P. 
PEAKE, J. F., 1968, Habitat distribution of Solomon Island land Mollusca. Symp. 

zool. Soc. Lond., No. 22: 319-346. 
PEAKE, J. F., 1969, Patterns in the distribution of Melanesian land Mollusca. Phil. 

Trans. Roy. Soc. B, 255: 285-306. 
PURCHON, R. D. & SOLARI, M. E., 1969, Studies on the distribution of species of 

Prosobranch and Pulmonate snails on the limestone hills of Malaya. Symposium 

on Mollusca, Mar. biol. Assoc. India, Pt. 1: 223-230. 
RENSCH, В., 1932, Über die Abhängigkeit der Grösse des relativen Gewichtes und 

der Oberflächenstruktur der Landschneckenschalen von der Umweltsfaktoren 

(Ökologische Molluskenstudien 1). Z. Morph. Ökol. Tiere, 25: 757-807. 
TWEEDIE, M. W. F., 1961, On certain Mollusca of the Malayan limestone hills. Bull. 

Raffles Mus., 26: 49-65. 



MALACOLOGIA, 1973, 14: 313-319 

PROC. FOURTH EUROP. MALAC. CONGR. 

POLYMORPHISME DU TEST DE POTAMOPYRGUS JENKINSI (E. A. SMITH, 1889) 
EN MILIEU SAUMATRE OU LACUSTRE 1 

Guy Real 

Institut de Biologie Marine, Arcachon, France 

RESUME 

Le test de Potamopyrgus jenkinsi, gasteropode Hydrobiidae des eaux douces 
ousaumâtres, peut présenter trois aspects; individus portant un test sans orne- 
mentation; individus présentant un test orné d'une carène continue ou enfin 
d'épines. 

L'auteur passe en revue les hypothèses émises quant aux facteurs, génétiques 
ou écologiques, susceptibles d'être à l'origine de ces ornementations. Il ap- 
porte en outre une contribution personnelle relative à l'observation de 35 sta- 
tions, douces ou saumâtres, du Sud Ouest de la France, dont il a régulièrement 
suivi la composition durant plusieurs années. Il conclut à la difficulté qu'il y a 
d'interpréter la nature et la fréquence des ornementations en fonction du seul 
facteur salinité. 

Potamopyrgus jenkinsi Smith est un Hydrobiidae récent pour l'Europe; l'espèce 
est actuellement encore en pleine expansion. Le problème de l'ornementation du test, 
qui reste à élucider, est un des sujets sur lequel beaucoup d'auteurs ont travaillé. 
Des observations sur le terrain, tant en milieux saumâtres que lacustres, permettent 
d'apporter un certain nombre de précisions. 

I. VARIATIONS MORPHOLOGIQUES DU TEST 

Dés la création de l'espèce, on s'aperçut que les divers spécimens de Hydrobia 
jenkinsi Smith = Potamopyrgus jenkinsi (Smith) présentaient des variations morpholo- 
giques du test. Très rapidement les auteurs créèrent des variétés en rapport avec 
ces variations. La coquille peut, en effet, présenter 3 aspects: 

- test à spire totalement dépourvue de toute ornementation 

= animaux à test lisse - variété "ecarinata" (Jenkins, 1889) 

- test à spire présentant une carène 

= animaux à test caréné - variété "carinata" (J. T. Marshall, 1889) 

- test à spire présentant une ligne de denticules ou épines 

= animaux à test à épines - variété "aculeata" (Overton, 1905) 

Cette terminologie est actuellement abandonnée. On a vainement essayé de vérifier, 
par des élevages, le caractère héréditaire de ces ornementations; on tend aujourd'hui 
à penser qu'elles sont en relation non pas seulement avec des facteurs génétiques, 
mais également avec les conditions écologiques externes. 

Enfin tous les intermédiaires entre le type caréné et le type à épines existent. La 
carène peut être réduite à une simple bande, même à peine visible, ou au contraire 
être très accentuée et donner une forme anguleuse à la spire en dessinant une véritable 
crête. La carène se situe approximativement sur le tiers supérieur des tours de 
spire et toujours parallèlement à leur ligne de suture. Les épines se situent exacte- 



Ije suis heureux de remercier Monsieur le professeur Amanieu qui est à l'origine de ce travail. 

(313) 



314 PROC. FOURTH EUROP. MALAC. CONGR. 

ment au même emplacement, elles sont généralement assez régulières, parfois 
accolées par groupe. Entre les épines, la carène est souvent faible ou même absente. 
Les deux formes, carénées et à épines, ne sont donc pas nettement distinctes. Dans 
certains cas, il semble même qu'il apparaisse d'abord une carène, les épines se dé- 
veloppant ultérieurement. 

IL PRINCIPAUX RESULTATS ANTERIEURS 

Welch (1898) avait constaté "la présence d'exemplaires carénés en eaux saumâtre 
et l'absence d'ornementation chez les animaux en eaux douce". Cette observation fut 
reprise par Seifert (1935) qui confirma, en 1938, que non seulement les individus 
carénés se trouvaient en eau saumâtre mais que le pourcentage de sujets carénés 
était en rapport très net avec la teneur en NaCl; ainsi "pour une salinité de 3% on 
avait plus de 50% d'individus carénés avec quelques uns à épines et à une salinité de 
5%o il n'y avait plus que 30% de lisses, 50% avait une carène et 20% des épines". 
Steusloff (1939) confirma cette interprétation; Adam (1942) écrit "tandis que le matériel 
provenant d'eau saumâtre comprend toujours un certain pourcentage de spécimens à 
coquille carénée ou même épineuse, celui provenant d'eau douce se compose exclusive- 
ment d'animaux à coquille lisse". Récemment Grossu (1966), après une étude statis- 
tique, constatait que dans les régions à salinité élevée, la majorité des exemplaires 
étaient carénés, tandis que l'on observait la situation inverse dans les régions plus 
lacustres. 

En revanche, d'autres auteurs estiment qu'il n'y a pas de relation directe entre 
l'ornementation de Potamopyrgus jenkinsi et la salinité du milieu; ainsi selon Robson 
(1926), Boycott (1929) et Warwick (1946), les formes ornées se trouvent indistinctement 
en eau douce et en eau saumâtre. D'autres auteurs enfin, tout en admettant que, 
généralement, le milieu saumâtre héberge des individus ornés signalent de nom- 
breuses exceptions, notamment Bondesen & Kaiser (1950), Lucas (1959-1963) et Mars 
(1961). Mais selon Petit & Veuillez (1962) "il est d'autre part un fait qui paraît certain, 
c'est que dans les eaux encore voisines du littoral, mais qui sont parfaitement douces, 
il n'y a plus d'individus carénés. Nous ne pouvons citer que 2 exemples mais ils 
sont nets". Pour terminer ce rapide tour d'horizon sur les observations des auteurs 
concernant l'ornementation en rapport avec le milieu je citerai Mars (1961) "en 
revanche, on ne semble pas avoir signalé de stations saumâtres (plus de 1% par 
mélange avec de l'eau de mer, distinction importante) où les populations soient toujours 
non carénées à 100%". 

Ш. OBSERVATIONS PERSONNELLES 

A. Formation de l'ornementation 

J'ai constaté que ni un nouveau-né, ni même un jeune des toutes premières semaines, 
ne présentent jamais la moindre trace de carène: en général l'ornementation apparaît 
seulement à partir de la taille 1,5 mm parfois plus, rarement moins. Quelques rares 
auteurs font état du nombre de tours de spire lors de l'apparition de la carène. Ainsi 
selon Boycott (1929) "les jeunes coquilles sont parfaitement lisses sur 2 spires au 
moins; la carène et les épines commencent sur la 3ème ou 4ème spire". De même 
Petit & Veuillez (1962) écrivent "la carène commence généralement sur le 3ème tour 
de spire et peut s'étendre jusqu'au tour médian. Dans certains cas assez rares, on 
peut constater, sur le même tour, l'amorce d'une autre carène et parfois d'une 3ème 
entre la première et la suture." Ces deux auteurs sont, je pense, les seuls qui sig- 
nalent une carénation multiple (c'est à dire 2 et même 3 carènes entre deux lignes 
de suture, donc sur le même tour de spire). Malheureusement il n'y a ni photographie 



REAL 315 

ni dessin pour illustrer ce cas. J'ai moi même trouvé deux individus qui semblaient 
présenter une deuxième carène parallèle à la première. Les photographies no 1 et 
no 2 montrent le même individu avec le début et la fin de cette carène supplémentaire« 

J'ai également trouvé 3 individus dont la carène, d'un type nouveau, présente un dé- 
crochement brutal qui la décale parallèlement à la ligne de suture. La photographie 
no 3 représente ce cas extrêmement rare de carène, le seul que j'ai observé sur plus 
de 20.000 individus et qu'il serait intéressant de retrouver. 

En revanche, j'ai constaté souvent des ornementations qui s'esquivaient pour ré- 
apparaître plus loin mais toujours dans le même alignement. 

Enfin la photographie no 4, inédite, présente un intérêt particulier en montrant que 
les modifications du milieu, se répercutant sur l'accroissement de la coquille, peuvent 
stopper net la fabrication de la carène à un moment précis. En effet, comme on peut 
le remarquer sur ce document à l'endroit où la coquille présente un accident dans la 
zone d'accroissement correspond l'arrêt brutal, complet et définitif de la carène. 

B. Stations prospectées et analyse comparative 
Pourtour du Bassin d' Ar cachón (Gironde) 

Dans cette région, 23 stations situées dans des étangs saumâtres, des zones d'estu- 
aires sujettes au jeu de la marée, et enfin dans les ruisseaux donnant dans le Bassin 
d'Arcachon, ont été régulièrement suivies: 

13 stations sont en eau douce (ruisseaux ou mares) - 10 en eau saumâtre (étangs et 
estuaires) 

Pour les stations saumâtres, à chaque prélèvement la salinité de l'eau a été re- 
cherchée par la méthode Harvey (solution de N03Ag à 27,25 gr/litre et 10 ml d'eau 
à analyser). Certaines de ces stations furent régulièrement suivies pendant 6 années 
voire 8 pour l'une d'entre elles. 

Région du sud ouest de la France (Arcachon jusqu'au Pyrénées) 

12 stations ont été prospectées, toutes en eau douce. 

Au total c'est donc 35 stations qui ont été étudiées. J'ai constaté: 

— que sur les 25 stations en eau douce, il y en a 19 qui présentent des individus ornés 
tandis que seulement 6 renferment des populations à test lisse à 100%. 

— que sur les 10 stations saumâtres il y a une population où les tests sont à 100% 
lisses et que 3 ne présentent que 1% environ de tests ornés. 

— de plus les stations où le pourcentage global d'individus carénés sur plusieurs 
prélèvements est le plus fort, se trouvent toujours être des stations en eau douce. 

— En ce qui concerne les populations à fort pourcentage d'exemplaires à épines, 
photographie no 5, c'est également dans des stations en eau douce que j'ai pu les 
récolter. Au contraire, les stations saumâtres ne présentent que peu ou pas d'indivi- 
dus avec des épines bien développées. 

C. Polymorphisme des populations en fonction du milieu 

1) La présence d'eau salée n' entraine pas obligatoirement la présence de l'orne- 
mentation. Une station appelée "réservoir de Chabaud" a été suivie pendant des 
années: l'eau y fut constamment saumâtre avec une amplitude importante de variations 
de la salinité comme le montre la Fig. 1. Or, dans cette station, sur environ 10.000 
individus que j'ai examines, aucun ne montra jamais la moindre ornementation. 

2) La présence d'eau salée n'est pas indispensable pour l'observation d'individus 
à coquille ornée. Dans le Sud Ouest de la France, à plusieurs kilomètres du littoral 
j'ai trouvé jusqu'à plus de 70% d'individus ornés et sur le pourtour du Bassin d'Arca- 
chon un petit ruisseau d'eau douce contenait une population ornée, en majorité à 
épines, à plus de 95%, mais elle était assez clairsemée. (Je n'ai récolté que 1.024 



316 



PROC. FOURTH EUROP. MALAC. CONGR. 




REAL 



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FIG. 1. Reservoir de Chabaud: Courbes des salinités, Année 1964: 3 dosages; Année 1965: 4 
dosages. Remarque: deux dosages consécutifs mais séparés par une longue période sont reliés 
par une ligne en pointillé. 



PHOTOGRAPHIE 1 , 2. Ces deux photographies du même test montrent le début et la fin de la 
deuxième carène qui est plus légère qu'une carène habituelle. On peut également remarquer 
que sur le dernier tour de spire les épines cessent et que seule demeure une carène. 

PHOTOGRAPHIE 3. Test avec une carène dont l'axe se trouve brutalement décalé par rapport 
à la ligne de suture. 

PHOTOGRAPHIE 4. Test présentant un arrêt brutal du développement de la carène correspon- 
dant à une zone de modification dans l'accroissement de la coquille. 

PHOTOGRAPHIE 5. Test découpé pour montrer les épines de profil. 

PHOTOGRAPHIE 6. Ces 2 tests montrent la variation de l'indice longueur/largeur que l'on 
peut rencontrer entre 2 populations. 



318 PROC. FOURTH EUROP. MALAC. CONGR. 

individus en 8 prélèvements ce qui est peu comparativement à la densité de la plupart 
des stations prospectées.) 

3) Des populations situées en eau douce permanente et lisses à 100% existent et 
sont quelquefois stabilisées dans le temps. 

Une population a été suivie pendant plus de 8 ans sans modification. Elle a été 
découverte par M. Amanieu en 1962 et est suivie depuis cette date; les individus y sont 
grands (jusqu'à 5,7 mm) et toujours lisses. 

4) Des populations situées en eau saumâtre permanente et lisses à 100% existent et 
sont quelquefois stables au cours du temps. Une population a été suivie pendant 7 
années avec plus de 70 prélèvements, sans jamais montrer un seul individu présentant 
la moindre ornementation. 

5) Je n'ai pas trouvé de populations présentant une ornementation à 100%. Des 
auteurs ont signalé des populations ornées à 100%. Il faudrait que quelques unes de 
celles-ci soient étudiées dans le temps et en précisant les conditions écologiques. 

6) D'après mes observations sur le terrain, les collections d'eau saumâtre dont la 
salinité moyenne est élevée, ne renferment pas un pourcentage d'individus ornés plus 
important que d'autres où la salinité est faible. 

7) Les plus forts pourcentages d'individus ornés se trouvent, d'après mes récoltes, 
dans les eaux douces. 

8) Dans une même population, je n'ai pu relever de différence sensible de la taille 
maximum entre les individus lisses et carénés. 

9) Des variations de taille, d'épaisseur de la coquille, de teinte, d'importance de la 
ponte, d'indice longueur /largeur du test existent chez certaines populations mais sont 
difficiles à schématiser de manière démonstrative. La plus frappante est certainement 
le rapport longueur/largeur de la coquille (photographie no 6). 

CONCLUSIONS 

Ces observations permettent de comprendre pourquoi les divergences des auteurs 
sont aussi fréquentes même actuellement. D'une part, il faut considérer que l'espèce 
est capable de s'installer dans des biotopes extrêmement variés: dans la mesure où 
l'on travaille en milieu saumâtre, le facteur salinité peut apparaître déterminant pour 
la présence de l'ornementation. D'autre part, les stations citées en eau douce parais- 
sent le plus souvent être à populations lisses mais elles sont encore peu nombreuses 
et souvent récentes. 

Je crois qu'il est encore nécessaire que quelques malacologistes continuent à suivre 
les populations qu'ils connaissent; ainsi, par la confrontation des résultats basés sur 
de longues observations sur le terrain, on arrivera à cerner le problème de l'orne- 
mentation. 

C'est dans cet esprit que j'ai entrepris récemment de transplanter des populations 
bien connues dans des milieux différents de leur habitat d'origine; malheureusement 
de telles expériences se heurtent à la difficulté qu'il y a à assurer une surveillance 
fréquente des animaux ainsi transplantés. 

BIBLIOGRAPHIE 

ADAM, W., 1942, Notes sur les gastéropodes, XI. Sur la répartition et la biologie de 
Hydrobia jenkinsi Smith en Belgique. Bull. Mus. Hist, natur. Belg., 18(23): 1-18. 

AMANIEU, M., 1962, Note sur l'écologie et la répartition dans la région d'Arcachon de 
Potamopyrgus jenkinsi (E. A. Smith). P. V. Soc. Linn. Bordeaux., 99: 1-8. 

BOETTGER, C. R., 1949, Hinweise Zur Frage der Keilbidung der Schale der wasser- 
schnecke Potamopyrgus crystallinus jenkinsi (E. A. Smith). Arch. Molluskenk., 



REAL 319 

77: 63-72. 
BOETTGER, C. R., 1954, La distribution actuelle de Potamopyrgus jenkinsi (E. A. 

Smith) en France. J. Conchol., 94: 31-38. 
BONDESEN, P. & KAISER, E. W., 1950, Hydrobia {Potamopyrgus) jenkinsi Smith in 

Denmark illustrated by its ecology. Oikos, 1(2): 252-281. 
BOYCOTT, A. E., 1929, The inheritance of ornementation in var. aculeata of Hydrobia 

jenkinsi Smith. Proc. malacol. Soc. Lond., 18: 230-235. 
GROSSU, A., 1966, Studiul populatiilor si polimorfismul la Hydrobia (Potamopyrgus) 

jenkinsi (Smith) din complexul Razelm. Extras Bucuresti, p 131-138. 
LUCAS, A., 1959, Remarques sur l'écologie d' Hydrobia jenkinsi (E. A. Smith), en 

France. J. Conchyliol. Paris., 100: 3-14. 
LUCAS, A., 1963, Hydrobia jenkinsi (Smith) dans la région Cantabrique (Espagne). Bull. 

Cent. Etud. Rech. Scient. Biarritz., 4(4): 375-378. 
MARS, P., 1961, Recherches sur quelques étangs dulittoral méditerranéen français et 

sur leurs faunes malacologiques. Thèse, Fac. Sei., Paris, Vie et Milieu 1966, 

suppl. 20: 1-270. 
PETIT, G. & VEUILLEZ, P., 1961, Notes sur l'écologie et la répartition de Potamo- 
pyrgus jenkinsi (E. A. Smith). С. r. 86e Congr. nat. Soc. sav. Montpellier Sec. 

se, p 763-767. 
ROBSON, G. C, 1926, Parthenogenesis in the mollusc Paludestrina jenkinsi. J. exp. 

Biol., 2(3): 149-160. 
SEIFERT, R., 1938, Die Bodenfauna des Greifswalder Boldens, ein Beitrag zur Ökolo- 
gie der Brackwasserfauna. Z. Morph. Ökol. Tiere., 34: 221-271. 
STEUSLOFF, U., 1939, Potamopyrgus crystallinus carinatus J. T. Marshall mit 

Kalkkielem auf der Schale. Arch. Molluskenk., 71: 82-86. 
WARWICK, T., 1946, The inheritance of the keel in Potamopyrgus jenkinsi (Smith). 

J. Conchol., 2(22): 200-202. 



MALACOLOGIA, 1973, 14: 321-325 

PROC. FOURTH EUROP. MALAC. CONGR. 

CONIDAE WITH SMOOTH AND GRANULATED SHELLS 

Henry E. Coomans 

Zoological Museum, Amsterdam, The Netherlands 

Ornamentation of the shell in the Conidae is very scarce. A number of species 
have small nodules at the shoulder, others have longitudinal ridges at the base of the 
last whorl. Conus sulcatus Hwass has spiral grooves over the whorls; this charac- 
teristic is also found in a few other species, e.g., C. austini Rehder & Abbot, C. 
granulatus Linné. In general the Cone shells are smooth. 

It has been known for a long time that some Conus species can be found in 2 
phenotypical different forms: the normal smooth shell, and the shell of the other form 
is covered with spiral rows of granulations over the last whorl. Martini (1773, 
Conchylien-Cabinet, vol. 2, p 273) described a granulated Conus ammiralis Linné as 
"Conus Architalassus granulatus." The name was used properly by Meuschen (1787, 
Museum Geversianum, p 346) as Conus ammiralis granulatus (Fig. 1), and this name 
was used by a number of authors (cf. Dautzenberg, 1937, p 21-22). 

Chemnitz (1788, Conchylien-Cabinet, vol. 10, p 83) described "Conus Terebellum 
violaceum granulatum, * which is a granulated Conus glans Hwass (Fig. 2). Lamarck 
(1822, Anim. s. Vert., vol. 7, p 514) mentioned this form as Conus glans var.b granu- 
lata. Dautzenberg (1937, p 129, pi. 1, fig. 11) also recognized a variety tenuigranulata, 
which should have smaller granulations. However, we consider tenuigranulata 
Dautzenberg a synonym of C. glans forma granulata Lamarck. 

Hwass (in Bruguière, 1792) described and figured Conus arenatus with a variety 
С "Testa granulosa" (Fig. 3), which was supposed to come from the Philippines. 

Reeve (1843, Conch. Icon., vol. 1, Conus spec. 197b) described a granulated form 
of Conus senator (=C. planorbis Born) with the "shell entirely granulated." 

Wils c.s. (1969 cont., p 60) described Conus catus var. granulata from Malaita, 
Solomon Islands. 

The authors mentioned above considered the smooth shell as the normal species, 
while the granulated specimens were varieties. A contrary opinion was held by 
Sowerby II (1857, Thes. Conchyl., vol. 3, Conus, p 2, pi. 1, figs. 6-7) who described 
Conus deburghiae (Fig. 4) as a granulated species, which had also a smooth variety. 

During 1967-1968 the Conus collection of the Zoological Museum in Amsterdam was 
revised by E. X. Maier, under supervision of the author. In his report Maier (1969) 
mentioned the occurrence of granulated forms in the following species: С achatinus 
Hwass; C. ammiralis Linné (Fig. 1); C. arenatus Hwass (Fig. 3); C. bandanus Hwass; 
С chaldeus Röding; С. furvus Reeve; C. glans Hwass (Fig. 2); С litoglyphus Hwass; 
C. lucidus Wood (Fig. 5); С musicus Hwass (Fig. 6); C. planorbis Born; C. striatellus 
Link; and C. vitulinus Hwass. Except for C. lucidus from the Eastern Pacific, all 
these species belong to the Indo-Pacific faunal province. According to Marsh (1964, 
p 146, pi. 21, fig. 7) the population of C. chaldaeus from Hawaii is granulated; the 
specimens from other places in the Pacific are smooth. 

Although it was well known that a number of Conidae are found with smooth and with 
granulated shells, as discussed above, some granulated Conidae were described as 
distinct species. The granulated Conus verrucosus Hwass (Fig. 8) from the West 
Indies is now united with the smooth C. jaspideus Gmelin. Modern authors consider 
verrucosus a variety or subspecies of C. jaspideus; both can be found together at 
the same locality (Abbott, 1958, p 17, map 10). The С jaspideus complex was discussed 

(321) 



322 PROC. FOURTH EUROP. MALAC. CONGR. 

by Abbott (I.e., p 88-91, pi. 3), who included many more Conus names in this complex. 

Reeve (1843, Conch. Icon., vol. 1, Conus spec. 115) already mentioned that Conus 
elventinus Duelos was a granulated variety of C. mindanus Hwass. However, other 
granulated Conidae were described by Reeve as distinct species. Conus metcalfii 
Reeve is now considered by most authors to be the granulated form of C. magus 
Linné, and C. rivularis Reeve (Fig. 10) represents the granulated form of С boeticus 
Reeve (Fig. 9). 

Other species pairs have been treated until now as 2 distinct species, and we sug- 
gest that they are the smooth and granulated forms of 1 single species. The smooth 
Conus sugillatus Reeve (Fig. 11) and the granulated C. muriculatus Sowerby II (Fig. 12) 
represent only 1 species. Since muriculatus was described in 1833 and sugillatus in 
1 844, the name of the granulated form has priority over the normal smooth shell. 
Conus flavidus Lamarck and the granulated C. frigidus Reeve {-maltzianus Weinkauff) 
may belong to 1 single species, although some further differences between these can 
be mentioned: frigidus has a rounded shoulder, a higher and straight spire which is 
spirally grooved, and a pink color, whereas flavidus is yellow. 

Conus puncticulatus Hwass (=C. pygmaeus Reeve) (Fig. 13) from the southern 
Caribbean has a granulated form which is known as C. pustulatus Kiener (Fig. 14). 

It remains questionable whether the smooth Conus bocki Sowerby HI, known from 
the Moluccas, and the sulcated C. sulcatus Hwass from China, belong to 1 species, 
comparable to the smooth and granulated Conidae. The occurrence of smooth and 
sulcated forms is known from other species; Abbott (1958, pi. 3, fig. i) mentioned a 
spirally grooved form of C. jaspideus. 

Two West Indian species, the smooth Conus mappa Lightfoot (Fig. 15), syn. cedonulli 
Hwass, dominicanus Hwass, insularis Gmelin, and the granulated Conus aurantius Hwass 
(Fig. 16) are considered by some authors (van Mol, Tursch & Kempf, 1967; Holeman 
& Kohn, 1970) as 1 single species. However, after studying a large number of speci- 
mens in several museums and private collections, Maier (1969) and the author are 
convinced that they represent 2 distinct species on the following grounds: 



FIG. 1. Conus ammiralis Linné forma. granulatus Meuschen, length 36 mm, Indonesia, Moluccas. 
(All photographs by L. A. van der Laan, Zoological Museum Amsterdam) 

FIG. 2. Conus glans Hwass forma granulata Lamarck, length 43 mm, Indonesia, Amboina Is. 
Conus arenatus Hwass forma granulosa Hwass, length 21 mm, Indonesia, Moluccas. 
Conus deburghiae Sowerby II, length 54 mm, Indonesia, Moluccas. 
Conus lucidus Wood, granulated form, length 25 1/2 mm, Galapagos Is. , Santa Cruz. 
Conus musicus Hwass, granulated form, length 18 mm, Indonesia, Moluccas. 
Conus jaspideus Gmelin, length 21 mm, West Indies. 

Conus jaspideus forma verrucosus Hwass, length 24 mm, Bahamas, N. Bimini. 
Conus boeticus Reeve, length 25 1/2 mm, Indonesia, Moluccas. 

Conus boeticus forma rivularis Reeve, length 34 mm, Indonesia, Moluccas. 

Conus muriculatus forma sugillatus Reeve, length 44 mm, Indonesia, Moluccas. 

Conus muriculatus Sowerby II, length 34 1/2 mm, Indonesia, Moluccas. 

Conus puncticulatus Hwass, length 23 mm, Netherlands Antilles, Curaçao. 

Conus puncticulatus forma pustulatus Kiener, length 22 mm, Netherlands Antilles, 

Conus mappa Lightfoot, length 49 1/2 mm, West Indies. 
Conus aurantius Hwass, length 40 mm, West Indies. 



FIG. 


3. 


FIG. 


4. 


FIG. 


5. 


FIG. 


6. 


FIG. 


7. 


FIG. 


8. 


FIG. 


9. 


FIG. 


10. 


FIG. 


11. 


FIG. 


12. 


FIG. 


13. 


FIG. 


14. 


Curaçao. 


FIG. 


15. 


FIG. 


16. 



COOMANS 



323 




324 



PROC. FOURTH EUROP. MALAC. CONGR. 



Conus mappa (Fig. 15) 

Shell wide (C. regius type) 

Length to 60 mm 

Spire with small nodules 

Shoulder smooth 

Last whorl smooth 

Color pattern very variable 

Spiral whorls with some very fine 

longitudinal grooves 
Wider distribution in the 

Caribbean 
In deeper water 



Conus aurantius (Fig. 16) 

Shell slender 

Length to over 70 mm 

Spire with larger nodules 

Shoulder nodulated 

Last whorl granulated 

Color pattern more uniform 

Spiral whorls smooth, except 

for growth lines 
Distribution limited to southern 

Caribbean 
In shallow water 



The occurrence of granulated forms in the Conidae is not related with any zoogeo- 
graphical province, since they are known from the Indo-Pacific, the West Indies, and 
the Panamic faunal province. The species in which we have found granulated forms do 
belong to a number of subgenera in the genus Conus (Conasprella, Chelyconus, Puncti- 
culis, Leptoconus, etc.); hence there is no relation between granulation and subgenus. 
All species discussed here are recent Conidae; however, also in fossil Conidae the 
occurrence of granulated forms is known. G. Spaink from the Dutch Geological Survey 
informed me that the 2 fossil Conidae found in the Netherlands, Conus dujardini 
Deshayes and C. antidiluvianus Bruguière, both from the European Miocene, are found 
with smooth and with granulated shells. 

Suggestions that smooth and granulated shells are connected with sexual dimorphism 
can be withdrawn, and it cannot be proved that different ecological conditions develop 
granulated shells. It seems more plausible that granulations are produced by muta- 
tions, in which case they deserve the status of a variety. 

As far as is known to me, granulated specimens are only known from the Conidae, 
and not from the related families in the superfamily Toxoglossa, the Terebridae and 
the Turridae. 

Dr. F. Starmühlner informed me that similar phenomena can be observed in the 
genera Neritina and Melanopsis. Some Neritina species are known with smooth and 
with spined shells, while the shell in Melanopsis can be unicolored or multicolored 
in the same species. These cases are related to the ecological circumstances, i.e., 
fresh and brackish water. The specimens from brackish water are smooth {Neritina) 
resp. unicolored (Melanopsis); in fresh water they become spined resp. multicolored. 

LITERATURE 



ABBOTT, R. T., 1958, The marine mollusks of Grand Cayman Island, British West 

Indies. Monogr. Acad, natur. Sei. Philad., 11. 
DAUTZENBERG, Ph., 1937, Resultats scientifiques du voyage aux Indes Orientales 

Néerlandaises, vol. II, fase. 18. Gastéropodes Marins 3. Famille Conidae. Mem. 

Mus. roy. Hist, natur. Belg., hors série. 
HOLEMAN, J. & KOHN, A. J., 1970, The identity of Conus mappa [Lightfoot], С. 

insularis Gmelin, С. aurantius Hwass in Bruguière, and Hwass's infraspecific 

taxa of C. cedonulli. J. Conchol., 27: 135-137, pi. 5. 
MAIER, E. X., 1969, Revisie van de Conidae in het Zoologisch Museum Amsterdam. 

(Unpubl. ms.) 



COOMANS 325 

MARSH, J. A., 1964, Cone shells of the world. Illustrated by О. H. Rippingale. Bris- 
bane, etc., 166p, 22 pis. 

VAN MOL, J. -J., TURSCH, B. & KEMPF, M., 1967, Mollusques Prosobranches: Les 
Conidae du Brésil. Ann. Inst, océanogr., 45: 233-255, pis. 5-10. 

WILS, E. es., 1969 cont., Familie Conidae. Edit. Conchyliol. Studiegroep "Xeno- 
phora," Antwerpen. 



MALACOLOGIA, 1973, 14: 327-331 

PROC. FOURTH EUROP. MA LAC. CONGR. 
A 16- YE AR SURVEY OF CEPAEA ON THE HUNDRED FOOT BANK 

C. B. Goodhart 

University Museum of Zoology, Cambridge, England 

INTRODUCTION 

The Hundred Foot Bank is a dead straight and highly uniform earthen dyke running 
beside the artificial New Bedford ("Hundred Foot") River across the fens, some 20 
kilometres northwest of Cambridge. It was originally built in 1652, when the fens were 
first drained for cultivation, but it has been reconstructed at various times and most 
recently in 1947-48, after a disastrous flood which left the bank as an island, with 
water on both sides, for upwards of 3 months. After this, the bank was heightened 
and levelled, mostly with silt dredged from the river, and it was re-seeded with grass 
in 1948, which is lightly grazed by cows and cut each summer. Over the past 20 years 
there has been some increase in weeds (nettles, cow parsley and thistles, mainly), 
but these are kept under control by spraying from the air, and the bank still appears 
to be remarkably uniform ecologically along its whole length. 

It supports a very abundant population of Cepaea nemoralis (Linnaeus), which 
shows significant variation in the frequency of different morphs over quite short 
distances, apparently unrelated to any vegetational or other ecological differences 
which, anyway, are minimal. I first surveyed the snail colony in 1952, taking samples 
at 200 metre intervals along 2 miles (3.2 kilometres) of the bank (Goodhart, 1962, 
which also gives a detailed description of the habitat, with photographs). But it was 
evident that these samples had been taken too far apart for there to be any correlation 
between neighbouring collections; and marking-recapture studies showed that the mean 
displacement of individual snails was only about 6 metres a year, the maximum ob- 
served being 16 metres. 

SAMPLING PROCEDURE 

So in 1953 a new series of samples were taken from 64 stations, exactly spaced and 
measured with a surveyor's chain, at intervals of l/8 furlong (27 l/2 yards = 25.15 m) 
along 1 mile (1609 m) of the bank, being the northern half of the 2-mile section examined 
in the previous year. All the stations were measured from an origin at 440 yards 
from the southern end, which was immediately opposite a ditch junction on the other 
side of the road beside the bank, its grid coordinate reference being 408767 on Sheet 
52/47 of the 1 /2 5, 000 Ordnance Survey map. 

Each sample comprised 50 adult Cepaea nemoralis, taken from the eastern face of 
the bank only, snails being less abundant on the western (river) face, which is partially 
submerged when the water is high in the winter. Four samples of 50 were collected 
in the months of May, June, July and August, from the 8 stations, starting with the 
southernmost, at 200 m intervals, and 2 samples of 50 each were collected in May and 
August from the 8 intermediate stations at 100, 300, 500, etc., metres, with 1 sample of 
50 being taken from each of the 3 stations at 25 m intervals between these others. 

Exactly the same sampling procedure was followed in 1961, nearly all the samples 
being collected within a week of the corresponding one 8 years before. This was 
repeated in 1969, except that as I was unable to start collecting until June the dates 
did not match so precisely those of the other 2 years. As well as being measured with 

(327) 



328 



PROC. FOURTH EUROP. MALAC. CONGR. 












К 



bo 
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о 

13 






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5- 



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GOODHART 329 

the chain, many of the positions could be related to fixed landmarks and I do not think 
that any of the collecting stations could have been misplaced by more than a metre or 
so over the whole 16 years. 

POPULATION NUMBERS 

In 1952 the Cepaea nemoralis population was very abundant indeed, ranging from 
about 5 to over 20 adults per square metre on the eastern slope of the bank, probably 
because all the rats, which seem to be the principal predators, had been drowned in 
the floods 5 years before. Since 1952 numbers have been more than halved, but the 
snails are still very plentiful and there seems to have been little change since 1961. 
Many rat-predated shells can now be found, but thrushes' anvils have only rarely 
been seen, and thrushes do not normally live in these open fens. Other birds, espe- 
cially rooks, probably also feed upon the snails. 

Cepaea hortensis (Müller) occurs only on one short section of 200 m of the bank 
between the stations at 300 and 500 m from the southern end, where it has never 
comprised more than 10% of the total Cepaea population. It was found along these 200 m 
which appear to be ecologically the same as the rest of the bank, in 1953, 1961 and 
1969, and there is no evidence of any significant change in its numbers relative to C. 
nemoralis over this period. 

GENETIC VARIATION AND STABILITY 

By way of illustration, Fig. 1 shows the percentages along the bank of 3 common 
phenotypes. These are Yellow shells, homozygous C^C^ and recessive to Pink and 
Brown; Banded shells, homozygous B - B~ and comprising all shells with any bands, 
recessive to Unbanded; and finally Brown shells, which because of a linkage disequili- 
brium in this colony are all Unbanded, carrying the dominant allele C-. It will be 
seen that there are large fluctuations in the proportions of these phenotypes along the 
bank, ranging from under 20% to over 90% for Yellow; from just over 20% to 100% for 
Banded; and from to 58% for Brown shells. 

A number of regular clines in morph frequency over distances of a few 100 m 
can be seen and, although there are some signs of a levelling out of the troughs and 
peaks of these fluctuations between 1953 and 1961, the main outlines have been pre- 
served with remarkable constancy over the 16 years. Most of the between-years 
variation is within the range of the 4 monthly samples taken from the 8 stations at 200 m 
intervals in each year (not shown in Fig. 1), which themselves showed no signs of any 
regular seasonal trends. None of this can be related to any observable ecological dif- 
ferentiation in what looks like an unusually uniform habitat. A similar state of affairs 
is found with all the other phenotypes which have been studied. 

LINKAGE DISEQUILIBRIUM 

Apart from the linkage disequilibrium already mentioned, resulting in a complete 
absence of Banded Brown shells, as is found in most other British colonies of Cepaea 
nemoralis, on the Hundred Foot Bank there is also a significant deficiency of Un- 
banded Pink shells, compared with Yellows. That is so along the whole 1600 m studied, 
except at one point 550 m from the southern end where in 1953 there was a highly 
significant excess of Unbanded Pinks. It was still there, and significant at the 5% 
level, in 1961; but by 1969, although there was still a small excess of Unbanded Pinks 
at this point, it was much reduced and well short of statistical significance. Whether 
the effect is being eliminated by selection, or simply swamped by immigration in 



330 PROC. FOURTH EUROP. MALAC. CONGR. 

from either side, cannot be determined. 

There also seemed in earlier years to have been a significant excess of Fused 
Bands among Pink shells, though this is now less well marked than it was before. 
Indeed, there may have been an overall decrease in band fusion, the inheritance of 
which is complex and not properly understood. If so, this probably constitutes the 
only major change in the colony over these 16 years, and one which presumably 
would have resulted from natural selection, though probably not by predators. 

AUTOCORRELATION WITH DISTANCE 

Fig. 2 shows the results of a computer study in which each of the 64 stations was 
correlated with its next neighbour at 25 m, then the next but one at 50 m, and so on, 
for their percentages of the same 3 phenotypes, namely Yellow, Banded and Brown. 
This shows significant correlation between samples collected 25 m apart, and usually 
also at 50 m, but beyond that correlation sinks rapidly to nil; it will be seen also that 
the histograms remained remarkably similar over the whole 16 years. This is another 
indication of the extremely low vagility of Cepaea nemoralis populations. 

CONCLUSIONS 

These observations show that important differences in the genetic composition of 
Cepaea nemoralis populations living in very similar habitats can be maintained 
unchanged for considerable periods of time, apparently without any differential en- 
vironmental selection whether by visual prédation or by adaptation to vegetational, 
edaphic, or micro-climatic differences, all of which seem to be minimal in this 
unusually uniform habitat. For example, the small-scale "area effect" for Brown 
shells, extending along about 100 m of the bank and quite sharply delimited (see Fig. 1) 
cannot possibly be attributed to any micro-climatic effect such as the ponding of cold 
air, which possibly favours this morph in some other situations (Cain, 1968). 

Of course the Cepaea on the Hundred Foot Bank must be subject to natural selection, 
like all other natural populations, but there is little reason to suppose that this, in so 
far as it is due to the external environment, should operate differently at different 
points along the bank, or that it could be responsible for the observed differences in 
the polymorphism of the snail population. 

A more likely explanation may be that snail numbers were much reduced during the 
flooding and re-building operations in 1947-48, and that chance differences ("founder 
effects") then arising in the surviving nuclear populations along the bank persisted 
during the subsequent great expansion in numbers, which reached its peak in about 
1952. The fact that these local differences in morph frequency have now been main- 
tained more or less unchanged for nearly 25 years, in the face of selection in a uniform 
environment, suggests that some genetic co-adaptation may have occurred and that 
the genetic differences between different sections of the colony, which will have had 
their origin in chance founder effects, may now be being maintained by selection. But 
this will be of an internal genotypic nature (and the occurrence of linkage disequilibria 
shows that this must be operating, at least to some extent), rather than being due to 
selective differences in the external environment. It remains to be seen whether 
selection for co-adaptation will be strong enough to outweigh the levelling effects of 
migration, slow as that certainly is. So far, most of the quite sharp local differentiation 
in morph frequency seems to have been quite stable. A similar mechanism has already 
been proposed (Goodhart, 1963) as a possible explanation for some of the large-scale 
"area effects" seen in other populations. 



GOODHART 



331 



YELLOW 



BANDED 



BROWN 



+0.5 г 



P<0-05 



1953 



-0.5 



гт-УЬ 



->I25 metres 



+0.5 г 



P<0-05 



о ------ 



961 



-0.5 



^ 



C£ 



CJ> 



+0.5 _ 



P <0-05 



1969 





-0.5 L 



FIG. 2. Correlation coefficient (r) for each of the 64 samples in Fig. 1 with its next neighbour 
at 25 m, its next but one at 50 m, and so on to 125 m, for the percentages of the 3 phenotypes in 
the samples, in 1953, 1961 and 1969. 

SUMMARY 

Significant local differences over distances of about 100 m in the polymorphism of 
a linear colony of Cepaea nemoralis living in an extremely uniform habitat, on an 
artificial river bank, have been maintained unchanged over 16 years. These are 
regarded as comparable with the larger "area effects* observed in other populations 
of this species, and it is suggested that they may be due to genetic co-adaptation 
resulting from founder effects when numbers were reduced, rather than to differential 
selective forces in the external environment. 

REFERENCES 

CAIN, A. J., 1968, Studies on Cepaea. V. Sand-dune populations of Cepaea nemoralis 

(L.). Phil. Trans. Roy. Soc, В., 253: 499-517. 
GOODHART, С. В., 1962, Variation in a colony of the snail Cepaea nemoralis (L.). 

J. anim. Ecol., 31: 207-237. 
GOODHART, С. В., 1963, "Area Effects" and non-adaptive variation between popula- 

tions of Cebaea (Mollusca). Heredity. 18: 459^46JL 



MALACOLOGIA, 1973, 14: 333-338 

PROC. FOURTH EUROP. MALAC. CONGR. 

ASPECTS GENERAUX DU POLYMORPHISME DE LA COULEUR DU 
PERISTOME CHEZ CEPAEA HORTENSIS EN FRANCE 



M. A. Guerrucci 



Ecole Normale Supérieure, Laboratoire de Zoologie, Paris, France 

Contrairement aux individus de l'espèce Cepaea nemoralis qui sont assez générale- 
ment caractérisés par la coloration brune de leur peristome, les C. hortensis ont 
le plus souvent un peristome blanc. Dans un assez grand nombre de colonies de C. 
hortensis il existe cependant aussi des coquilles à peristome coloré en brun, en brun 
clair ou en rose. 

Le caractère peristome coloré se retrouve chez Cepaea hortensis dans la plupart 
des régions de France, avec des fréquences très variables. Pour faire apparaître 
les différences entre ces régions on a estimé, pour un certain nombre d'entre elles, 
la fréquence moyenne du caractère peristome blanc. Les différentes valeurs obtenues, 
reportées sur la carte de France (Fig. 1), montrent l'existence d'une variation géo- 
graphique importante. 

C'est dans la vallée de la Loire, particulièrement entre Tours et Blois, où certaines 
colonies présentent parfois moins de 10% de peristomes blancs que la fréquence 
moyenne du caractère est la plus faible. Sa valeur varie peu le long de cette vallée, 
mais elle augmente, en revanche, assez rapidement dans les régions voisines. Elle 
atteint 90% dans le Pyrénées, en Normandie, dans le Nord et dans l'Est. Cette pré- 
pondérance des peristomes blancs dans les régions périphériques est en accord avec 
les observations effectuées en Espagne, en Angleterre, aux Pays Bas et en Allemagne, 
où la présence d'individus à peristome coloré est signalée comme rare. 

La variation clinale du caractère peristome blanc est parfois très sensible à 
l'échelle locale. Le phénomène est particulièrement net en Touraine où la fréquence 
des peristomes blancs augmente progressivement vers l'amont des vallées du Cher 
et de l'Indre, affluents de la Loire (Fig. 2). La fréquence du caractère atteint même 
100% dans les populations les plus éloignées. 

Dans la vallée de l'Aube, il est possible de distinguer, parmi les populations étudiées, 
un groupe situé à l'ouest d'Arcis-sur-Aube, distant de 15 kilomètres environ d'un 
autre groupe situé à l'est. La fréquence moyenne du caractère peristome blanc, qui 
est de 60% à l'ouest, passe à 83% dans le secteur oriental (Fig. 3). Les deux groupes 
d'échantillons diffèrent significativement en ce qui concerne ce caractère (P<10~ 4 ). 
Toutefois le gradient apparaît moins nettement qu'en Touraine. П est en effet dis- 
simulé par les variations assez notables de la fréquence d'une colonie à l'autre. 

Les écarts observés entre les fréquences peuvent être attribués en partie à des 
fluctuations d'échantillonnage ou encore à des phénomènes de dérive, d'autant plus 
que les échanges entre populations demeurent très limités, car la plupart d'entre 
elles sont distantes de plusieurs kilomètres. En outre, comme le caractère peristome 
blanc est souvent assez étroitement associé à d'autres caractères de coloration de la 
coquille, sa fréquence peut se trouver en partie conditionnée par celle des caractères 
qui lui sont associés. 

L'importance des fluctuations de la fréquence du caractère dans les populations 
situées à l'intérieur d'un secteur limité est mise en évidence sur les histogrammes de 



1 Adresse postale: Laboratoire de Zoologie ENS, 46 rue d'Ulm, Paris 5e, France. 

(333) 



334 



PROC. FOURTH EUROP. MALAC. CONGR. 




100km 



FIG. 1. Fréquences régionales moyennes (en 9r) du caractère Peristome blanc. 



la Fig. 4. Dans les différents secteurs de la vallée de la Loire observés, la fréquence 
oscille entre et 40%. Les variations sont de même amplitude dans chacun des deux 
groupes de populations de la vallée de l'Aube, ainsi que dans la vallée de l'Eure. 
Dans le département de la Marne la fréquence du caractère est presque toujours 
supérieure à 90%; elle atteint même 100% dans plusieurs populations. 

Au total, les distributions correspondant à chacun des secteurs sont assez homogènes 
et montrent que, localement, la fréquence du caractère peristome blanc est relative- 
ment stable; l'estimation de la fréquence moyenne à l'intérieur d'une région est donc 
une bonne image de la fréquence du caractère dans ces régions. 

La variation clinale de la fréquence d'un caractère n'est pas un phénomène rare et, 
chez de nombreuses espèces continentales, il est courant qu'un ou plusieurs caractères 
présente de semblables variations. D'autres gradients ont d'ailleurs été mis en 
évidence chez Cepaea hortensis, en particulier pour le sytème de bandes 10305 (12). 
De telles variations géographiques sont généralement en relation avec une variation 
graduelle des facteurs climatiques de l'environnement. Cependant l'aspect rayonnant 
du cline rend difficile à priori l'hypothèse l'une simple action sélective par des 
facteurs climatiques car, dans des régions présentant des caractéristiques climatiques 
aussi différentes que le Nord, l'Est, le Sud et le Sud-Ouest de la France, le caractère 
se présente avec des fréquences identiques. 

Le gradient mis en évidence peut être rapproché des observations concernant la 



GUERRUCCI 



335 





FIG. 2. Fréquence du caractère Peristome blanc dans les populations de Touraine. 

FIG. 3. Fréquence du caractère Peristome blanc dans les populations de la vallée de l'Aube. 



336 



PROC. FOURTH EUROP. MALAC. CONGR. 



secteur INDRE et LOIRE 
LOIR et CHER 
m=17 



t=r- 



if. 



О 50 

vallée de TEURE 



m=67 



100 



secteur LOIRET 
m = 22 



secteur NIÈVRE 
m=23 



ч- 



50 

vallée de la LOIRE 



~ I 

100 



ouest d'ARCIS 
m=60 



15_ nb colonies 



^d 



est d'ARCIS 
lm=83 



50 100 

vallée de ГАиВЕ 



-R- 



m=92 



50 
MARNE 



FIG. 4. Distribution des fréquences du caractère Peristome blanc à l'intérieur de différents 
secteurs géographiques. - en abcisse : fréquence (en %) du caractère Peristome blanc; - en or- 
donnée : nombre de colonies (le repère placé sur l'axe de ordonnées indique le nombre de colonies 
où la fréquence du caractère est de 0% ou de 100%). 

répartition du caractère peristome blanc chez Cepaea nemoralis . Ce caractère est 
sans doute contrôlé par un gène P A récessif par rapport au gène P N qui détermine la 
coloration normale du peristome (3.8). Il est rare parmi les individus de cette 
espèce et n'a été recontrê avec une fréquence importante que dans des régions 
isolées ou à la limite de l'aire de répartition [ouest de l'Irlande, (5.6.9.), Ecosse, 
(1), nord de l'Allemagne (13.14), Pyrénées (2.10)]. Il est possible d'envisager que 
le gène P N , apparu au centre de l'aire de distribution, ait été favorisé et soit parvenu 
à éliminer progressivement son allele sauf dans les régions où les populations sont 
relativement isolées. Cain a effectivement pu observer dans certaines localités du 
sud de l'Angleterre une diminution de la fréquence du caractère peristome blanc 
entre le néolithique et l'époque actuelle (4). 



GUERRUCCI 337 

Etant donné l'étroite parenté génétique entre les deux espèces on est tenté de re- 
tenir un hypothèse semblable pour interpréter les variations observées chez Cepaea 
hortensis. Il faudrait alors supposer soit qu'une mutation du gène s'est produite en un 
point bien déterminé de l'aire de l'espèce et s'y est répandue dans les populations, 
soit qu'il y a eu, à une époque donnée, une introgression entre les deux espèces. 
Cette dernière hypothèse est étayêe par la similitude plus grande de la coquille des 
deux espèces dans le centre de la France, à tel point que, dans les populations mixtes 
la seule observation de la coquille ne permet souvent pas de l'identifier. Le caractère 
ainsi apparu chez C. hortensis aurait ensui te, comme chez C. nemoralis mais avec 
une réussite moins totale, diffusé à travers les diverses populations. 

BIBLIOGRAPHIE 

1) ARNOLD, R. W., 1966, Factors affecting gene-frequencies in British and Conti- 

nental populations of Cepaea. D. Phil, thesis, Oxford. 

2) ARNOLD, R. W., 1968, Climatic selection in Cepaea nemoralish. in the Pyrénées. 

Phil. Trans. Roy. Soc, London, В 253: 549-593. 

3) CAIN, A. J., KING, J. B. M., SHEPPARD, P. M., 1968, The genetics of some 

morphs and varieties of Cepaea nemoralis L. Phil. Trans. Roy. Soc, London, 
В 253: 383-396. 

4) CAIN, A. J., 1971, Colour banding morphs in subfossil samples of the snail Cepaea. 

In: Ecological genetics and evolution. R. Creed, 65-92. 

5) CAMERON, R. A. D., 1969, The distribution and variation of Cepaea nemoralis 

L. near Slievecarran, County Clare and County Galway, Eire. Proc. malacol. 
Soc. London, 38: 439-450. 

6) CLARKE, В., DIVER, C, MURRAY, J., 1968, The spatial and temporal distribution 

of phenotypes in a colony of Cepaea nemoralis L. Phil. Trans. Roy. Soc, 
London, В 253: 519-548. 

7) COOK, L. M., 1966, Note on two colonies of Cepaea nemoralis L. polymorphic for 

white lip. J. Conchol., 26: 125-130. 

8) COOK, L. M., 1967, The genetics of Cepaea nemoralis. Heredity, 22: 397-410. 

9) COOK, L. M., PEAKE, J. F., 1960, A study of some populations of Cepaea nemor- 

alis L. from the Dartry Mountains, Co. Sligo, Ireland. Proc malacol. Soc 
Lond., 34: 1-2. 

10) GUERRUCCI, M. A., 1971, Etude de la transmission de quelques caractères de la 

pigmentation chez Cepaea hortensis. Arch. Zool. exp. gén., 112: 211-219. 

11) LA MOTTE, M., 1972, Le caractère "peristome blanc" dans les populations de 

Cepaea nemoralis L. (Moll. Pulmones) de la vallée de l'A riège. C.r. Acad. 
Sei., 274: 1558-1561. 

12) LAMOTTE, M., GUERRUCCI, M. A., 1970, Traits généraux du polymorphisme du 

système de bandes chez Cepaea hortensis en France. Arch. Zool. exp. gén., 
3: 393-409. 

13) SCHILDER, F. A., SCHILDER, M., ' 1953, Die Bänderschnecken (Monographie 

Hiddensee). Jena, p 1-90. 

14) SCHILDER, F. A., SCHILDER, M., 1957, Die Bänderschnecken Europas. Jena, 



p 91-206. 



SUMMARY 



In contrast to individuals of the species Cepaea nemoralis which are generally 
characterized by their brown lip, C. hortensis more often possesses a white lip. 
However in France shells with a brown, light brown or pink lip also occur in a 
relatively large number of C. hortensis colonies. 



338 PROC. FOURTH EUROP. MALAC. CONGR. 

The spatial distribution of the average frequency for the white lip estimated in a 
certain number of French regions shows the existence of a significant geographic 
variation. The frequency of the white lip, very rare in the Loire valley, gradually 
increases in the neighboring regions and reaches 90% in the Pyrenees, in Normandie, 
in the north and the east. The preponderance of white lip observed in the peripheral 
regions corresponds to the results reached in England, in the Netherlands, in Germany 
and in Spain where the presence of colored lip individuals has been noticed as a rare 
event. 

One can also observe at a local level the clinal variation of the phenotype. The 
frequencies of the white lip are however relatively stable within a limited sector. 



MALACOLOGIA, 1973, 14: 339-343 

PROC. FOURTH EUROP. РДАЬАС. CONGR. 

AN EXAMINATION OF THE DISTRIBUTION OF SHELL PATTERN IN 

LITTORINA SAXATILIS (OLIVI) WITH PARTICULAR REGARD TO THE 

POSSIBILITY OF VISUAL SELECTION IN THIS SPECIES 

Charles Pettitt 

Manchester Museum, The University, Manchester, England 

ABSTRACT 

Previous reports of crypsis in prosobranchs are briefly reviewed. Prelimi- 
nary data are presented which indicate that Littorina saxatilis with patterned 
shells tend to be associated with backgrounds upon which they are cryptic. The 
suggestion is made that visual selection, probably by birds or crabs, must be 
considered as a factor influencing this distribution. 

INTRODUCTION 

The rough winkle, Littorina saxatilis (Olivi 1792), is highly polymorphic for a 
number of shell characters such as shape, sculpture and shell thickness. However, 
it is probably the striking variation in the colour and pattern of the shell in this 
species which has attracted most attention from malacologists. The colours found 
range from white through grey, fawn, brown, purple, red, orange and yellow to black. 
After a careful study of numerous shells it has proved possible to score the varieties 
of shell ground colour using 7 broad colour classes. Some interesting variations in 
percentage frequency of the different ground colours have been found in contiguous 
populations and in serial samples; these results will be reported in detail elsewhere. 

In addition to differing ground colours, patterns composed of 1 or more colours or 
shades superimposed on a different ground colour or shade are also frequent. These 
patterns may consist of well defined bands (1 or 2, rarely 3); such shells were scored 
as B + . Continuous or interrupted lines and a great variety of flecks, hyphens, spots, 
patches, tessellations, flammules and zigzags, etc., also occur; these shells were all 
scored as 'tessellate' (T + ). The possibility that these morphs might show associations 
with the nature of the background was thought to be worth investigating. 

Very few earlier references to crypsis in intertidal prosobranchs have been found. 
Cooke (1895) mentions 3 examples of what he considered to be protective colouration, 
1 in the tropical Littorina (=Tectarius) pagodus, which closely resembled its back- 
ground rock; another in some black and white banded Thais lapillus at Newquay, on 
rocks which were variegated with white and other colours; and finally he noted that L. 
obtusata closely resembled the bladders of Fucus vesiculosus upon which it lived. 
This crypsis of L. obtusata was also remarked upon by Walton (1915), and has been 
found to apply also to snails on Ascophyllum nodosum (pers. observ.). 

Blaney (1904), studying Thais from a number of islands off Maine, U.S.A., found the 
bright yellow morph to predominate over the other kinds on Yellow Island, where the 
rocks were yellow or reddish. Colton (1916), again working with Thais, this time at 
Mount Desert Island, Maine, found more light coloured shells on red rocks than on black 
rocks, although yellow was equally common on both. He also offered a small amount 
of evidence showing a tendency for banded Thais to be associated more with striped 
schist than with plain red granite. 

The observations of all these authors were based on small numbers of shells. 
However, Cain & Sheppard(1950), in their classic paper on selection in the polymorphic 

(339) 



340 PROC. FOURTH EUROP. MALAC. CONGR. 

land snail Cepaea nemoralis, found a strong correlation between the amount of vari- 
egation of the habitat background and the amount of banding of the shells; this obser- 
vation has since been thoroughly confirmed. It was therefore decided to examine from 
a similar standpoint some accumulated data on the relative frequencies of banded and 
tessellate morphs of Littorina saxatilis from various habitats. 

MATERIALS AND METHODS 

Eleven populations from 8 localities on the west coast of England and Wales were 
scored. It was found possible to divide the habitats from which the samples had been 
collected into 'variegated': e.g., rocks or, particularly, groynes covered in barnacles 
and small seaweeds, or rocks with many flecks and veins of contrasting colour in them; 
and 'non-variegated': monochrome rockfaces and boulder shores. 

It was further possible to divide the habitats into 'open': rockfaces or groynes sides 
where the snails are exposed to view for a considerable part of the time, and 'con- 
cealed': such as rocks with many crevices, or, particularly, shores where boulders 
piled up 2 or more deep allow the snails to spend much of their time hidden from view 
under or between the boulders. 

It was noticed while collecting that banded shells, particularly white banded ones, 
tend to be conspicuous on both variegated and non-variegated shores, whereas tessel- 
late shells were conspicuous on non-variegated but tended to be cryptic against 
variegated ones. No concealed but variegated shore was found. 

RESULTS 

Table 1 gives the numbers of banded and of tessellate shells, together with the total 
sample size for each of the 11 samples; in 3 of the localities samples were taken from 
2 different but contiguous backgrounds. The relative frequency between each of the 2 
factors for both the morphs may be summarised thus: 

B + T + 



variegated 


high 


high 


unvariegated 


low 


low 


open 


low 


high 


concealed 


high 


low 



The summed percentage frequency of the 2 morphs found on the various combinations 
of habitat type are given in Table 2. 

The frequency of banding was significantly higher in samples from variegated and 
from concealed shores (p< 0.001 for both). Highly significant heterogeneity in banding 
exists between the various samples (X X q =521.15; p<<0.001). The heterogeneity of 
banding was determined between the 3 combinations of habitat type found, using summed 
data; this heterogeneity was significant (Х^ЭЗ.86; p<0.001), and was caused mainly 
by the association of banded shells with open variegated and with concealed variegated 
shores, while shells on open unvariegated shores tended to be unbanded. 

However the residual heterogeneity was still highly significant (x| = 521.15 -93.86 = 
427.29), indicating that other factors are involved also in determining the distribution 
of these morphs. 

The frequency of tessellation was significantly higher in samples from variegated 
backgrounds and from open shores (p< 0.001 for both). There was significant hetero- 
geneity in tessellation between the various population samples (X 10 = 5231.28; 
p < < 0.001). The heterogeneity of tessellation was determined between the 3 combi- 
nations of habitat type, using the summed data; this heterogeneity was significant 
(x|= 326.12; p< < 0.001), and was due chiefly to the association of tessellate shells 



PETTITT 341 

TABLE 1. Frequency of banded and tessellate morphs on different backgrounds. 



Population 


Habitat description 


Habitat type 


Frequency 
B + T + 


Sample 
size 


Red Reef 


red rock with streaks 
and spots of white 


variegated 
open 


7 


8 


87 


Hoylake 


fawn/grey boulders 


unvarie gated 
concealed 


17 


8 


357 


Mumbles 


grey rockface 


unvariegated 
open 


1 


2 


99 


Mumbles 


grey boulders 


unvariegated 
concealed 


7 





121 


Llanf air fechan 


groyne with barnacles 


variegated 
open 


204 


55 


771 


Llanfairf echan 


fawn boulders 


unvariegated 
concealed 


92 


19 


264 


Amroth 


brown/grey boulders 


unvariegated 
concealed 


2 


5 


94 


Amroth 


groyne with barnacles 


variegated 
open 


28 


270 


906 


Oxwich 


grey rockfaces 


unvariegated 
open 


7 





606 


Port Eynon 


grey boulders 


unvariegated 
concealed 


5 





56 


Port Erin 


black rockfaces 


unvariegated 
open 


1 


5 


50 






Total 


s: 371 


372 


3411 



TABLE 2. Percent frequency of banded and tessellate morphs on different 
backgrounds. 





Concealed shores 


Open shores 






mean T + = 18.9% 


variegated 
appearance 




S.D. = 7.2 
N. = 1764 
mean B + = 13.5% 
S.D. = 7.1 




mean T + = 3. 6% 


mean T + = 0. 9% 


unvariegated 
appearance 


S.D. = 1.4 
N. = 892 
mean B + = 13.8% 


"S.D. = 3.0 

N. = 755 
mean B + = 1.2% 




S.D. = 6.4 


S.D. = 0.4 



342 PROC. FOURTH EUROP. MALAC. CONGR. 

with variegated open shores; populations in the other 2 habitat types tended to be non- 
tessellate. 

Once more, however, the residual heterogeneity was highly significant (X^ = 
5231.28-326.12 = 4905.16), indicating that other factors again must be involved in 
determining the distribution of this morph. 

DISCUSSION 

The data here presented indicate that there is a tendency for patterned shells to be 
associated with habitats where they are most cryptic, although obviously much more 
information is needed before any firm conclusions can be drawn. 

In the absence of any evidence that shell colour is either linked to, or has a pleio- 
trope relation to, the other variable characters such as shell thickness, sculpture, 
resistance to desiccation, etc., the only selective force likely to be of importance in 
governing the distribution of the colour morphs of Littorina saxatilis is visual selection. 
From a review of the predators of this species (to be published elsewhere) it is apparent 
that the most important visual selectors of the snails are birds and crustaceans, 
particularly crabs. 

Giesel (1970) found the limpet Acmaea digitalis , in a panmictic unit, to be dimorphic, 
with light and dark morphs. The dark morphs were associated with dark rocks, and 
the light morphs with rocks encrusted with white barnacles. The young of each 
morph settle equally on both substrates and the bimodal distribution of the adults 
appears to be established by visual selection of the young snails by shore birds. 

As Littorina saxatilis is viviparous the explanation of the association found of B + 
and T + morphs with different substrates cannot be exactly the same. The spat of 
L. saxatilis tend to remain in the vicinity of the parent, and the active dispersal rate 
of the adults is slow, about 0.5 to 10 m per year (Herdman, 1890; Gowanloch & Hayes, 
1926; Lami, 1937; Berry, 1961; James, 1968). Thus if the frequencies of T + were 
initially identical on, say, a plain rockface and a continuous barnacle encrusted 
rockface, visual selection would alter this equality; assuming T + to be inherited, the 
increased frequency of T + on the barnacle face, and the reduced frequency on the 
plain rock would tend to be maintained by later generations, whether the selection was 
intermittent or even ceased altogether. 

As the number of samples in the present study is small, the possibility cannot be 
dismissed, however, that these morphs may have become initially associated with 
their present backgrounds by chance. Again, tessellate and non-tessellate morphs 
may initially actively select a cryptic background, as do the light and dark morphs of 
the moth Bistort betularia (Kettlewell, 1955). 

However, the present results indicate that visual selection should be considered as 
a factor determining the distribution of the tessellate and banded colour morphs of 
Littorina saxatilis. 

ACKNOWLEDGEMENTS 

I thank Dr. L. M. Cook for his helpful suggestions and criticisms at all stages of 
the preparation of this paper, and especially for his assistance with the statistical 
work. 

LITERATURE CITED 

BERRY, A. J., 1961, Some factors affecting the distribution of L. saxatilis (Olivi). J. 
anim. Ecol., 30: 27-45. 



PETTITT 343 

BLANEY, D., 1904, List of shell-bearing Mollusca of Frenchman's Bay, Maine. Proc. 

Boston Soc. natur. Hist., 32: 23-42. 
CAIN, A. J. & SHEPPARD, P. M., 1950, Selection in the polymorphic land snail 

Cepaea nemoralis. Heredity, 4(3): 275-294. 
COLTON, H. S., 1916, On some varieties of Thais lapillus in the Mount Desert Region, 

a study of individual ecology. Proc. Acad, natur. ScL Philad., 68: 440-454. 
COOKE, A. H., SHIPLEY, A. E. & REED, F. R. C, 1895, Molluscs. Vol. 3, Cambridge 

natur. Hist. 535 p. 
GIESEL, J. T., 1970, On the maintenance of a shell pattern and behaviour polymorphism 

in Acmaea digitalis, a limpet. Evolution, 24: 98-119. 
GOWANLOCH, J. N. & HAYES, F. R., 1926, Contributions to the study of marine 

gastropods I: the physical factors, behaviour and intertidal life of Littorina. 

Contr. Can. Biol. Fish., [NS] 3: 133-162. 
HERDMAN, W. A., 1890, Third Annual Report of the Liverpool Marine Biological 

Station on Puffin Island. Proc. Trans. Lpool. biol. Soc, 4: 36-82. 
JAMES, B. L., 1968, The occurrence of Parvatrema homeotecnum James 1964 

(Trematoda: Gymnophallidae) in a population of Littorina saxatilis tenebrosa 

(Mont.). J. natur. Hist., 2: 21-37. 
KETTLE WELL, H. B. D., 1955, Recognition of the appropriate background colours by 

the pale and black phases of Lepidoptera. Nature, 175: 943-944. 
LAMI, R., 1937, Sur des 'champs de pâture' de colonies de Littorina saxatilis (Olivi). 

Bull. Lab. marit. Dinard, 17: 41-43. 
WALTON, С. L., 1915, The distribution of some littoral Trochidae and Littorinidae 

in Cardigan Bay. J. mar. biol. Assoc. U.K., 10: 114-122. 



MALACOLOGIA, 1973, 14: 344 

PROC. FOURTH EUROP. MALAC. CONGR. 
PREDICTION OF THE NUMBER OF COLOR MORPHS IN POPULATIONS OF LIGUUS FASCIATUS 

Michael A. Rex* 
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, U.S.A. 

ABSTRACT 2 

Liguus fasciatus is a highly polymorphic arboreal pulmonate inhabiting small islands called hammocks 
in southern Florida and hardwood groves in Cuba and Haiti. The present study concerns those living on 
hammocks in Long Pine Key, Florida. Hammocks are islands of tropical hardwood vegetation surrounded 
by sparse sandy pine wood or swamp. In Long Pine Key, hammocks range in size from 0.34 to 43.80 acres. 
The Liguus material, collected in 1931 by W. J. Clench and W. S. Schevill, included 9 color morphs: ebur- 
neus, cingulatus, roseatus, castaneozonatus, deckerti, luteus ,ornatus , testudineus, marmoratus (see Pilsbry, 
1946). 

Computerized stepwise multiple regression analysis (Dixon, 1968) was performed to determine whether 
the number of color morphs in populations of Liguus living on 48 individual hammocks in Long Pine Key 
could be predicted by any of the following set of independent variables: X v hammock area; X 2 , distance 
to the largest hammock; X 3 , distance to the largest hammock > 20.0 acres (there were 6 hammocks of 
this size); X 4 , distance to nearest hammock; X 5 , size of nearest hammock. Variables X 2 - X 5 were 
thought to measure isolation. The statistic R 2 estimates the variance in the dependent variable (number 
of color morphs) "explained" by the combined effects of the independent variables. 

The regression as a whole provided a significant prediction of the number of morphs (R 2 = .39, F ( 5j 42 \ = 
5.372, P < .01). A significant positive correlation existed between the number of morphs and hammock 
area (contribution to R 2 = .30, t/ 42 \ = 4.5705, P < .001; but variables measuring isolation, with the exception 
of X 2 , proved insignificant. Distance to the largest hammock (X 2 ) was significant (contribution to R 2 = .07, 
t(42) = 2.2924, P < .05), but subordinate to the effect of area. 

I infer from the relative ineffectiveness of isolation variables to predict the number of morphs in the 
multiple regression and the general widespread distribution of morphs in this group of hammocks that 
inter-hammock migration is extensive, but that its contribution to maintaining polymorphism is strongly 
mediated by hammocksize. Polymorphism is evidently not random as Pilsbry (1912, 1946) suggested. Some 
form of selection appears to reduce the color variation of populations on small hammocks. What the 
selective agent(s) might be is uncertain. One possibility is that the various morphs are aposematically 
(Eisner & Wilson, 1970) or cryptically colored and that smaller hammocks support less variable popula- 
tions because they afford fewer possibilities for aposematic or cryptic associations to avoid visual predators. 
Predators on Liguus include several birds (Simpson, 1929) and the opossum (Pilsbry, 1946). 

LITERATURE CITED 

DIXON, W. J. [ed.], 1968, Biomedical computer programs. University of California Publications in Auto- 
matic Computation, No. 2. Univ. California Press, Berkeley. 600 p. 

EISNER, T. & WILSON, E. O., 1970, Defensive liquid discharge in Florida tree snails (Liguus fasciatus). 
Nautilus, 84: 14-15. 

PILSBRY, H. A., 1912, A study of variation and zoogeography of Liguus in Florida. J. Acad, natur. Sei. 
Philad., 15: 429-471. 

PILSBRY, H. A., 1946, Land Mollusca of North America. J. Acad, natur. Sei. Philad. Monographs No. 3, 
2: 1-520. 

SIMPSON, С T., 1929, The Florida tree snails of the genus Liguus. Proc. U. S. natn. Mus., 73: 1-44. 



1 Present address: University of Massachusetts - Boston, Boston, Massachusetts, U.S.A. 
^Published in extenso in Breviora, 1972, 391: 1-15. 



(344) 



MALACOLOGIA, 1973, 14: 345-347 

PROC. FOURTH EUROP. MALAC. CONGR. 
LITHOPHAGA LITHOPHAGA (L.) (BIVALVIA) IN DIFFERENT LIMESTONE 

Karl Kleemann 
/. Zoologisches Institut der Universität Wien, Austria 

The purpose of this study is to determine the boring rate of Lithophaga lithophaga 
(L.) with respect to different kinds of limestone, in field and laboratory investigations. 
Up to the present time, no experiments have shown the influence of the different 
morphological texture and the chemical composition of limestone on the boring rate. 
Hodgkin (1962) put specimens of L. plumula kelseyi Hertlein & Strong 1946 in holes 
bored in limestone rock as well as in non-calcerous mudstone in order to determine 
whether they bore by some sort of chemical or mechanical means. By this approach 
he provided a successful method. 

The author prepared 8 different limestone rocks with holes 12 mm wide and 30 mm 
deep according to the method of Hodgkin, 1962. 1) These are samples from the area 
investigated at Rovinj, Yugoslavia: BA and BRbl originate from the island Banjole; 
V is a boulder from the Vestar-bay. 2) The samples IH, Ц, W, GM and KK are not 
from Rovinj; they consist of calcite as the above-mentioned, without showing essential 
chemical differences with regard to further components (mainly quartz), with the 
exception of KK, which is interspersed with ferric-oxide-hydrates (Limonite). 

The rocks are determined by X-ray diffraction and thin-sections. Each sample 
contains 3 mussels approximately 30 mm long marked by etching numbers on the 
shell and the measures and weight of each mussel are recorded. Field investigations 
are adapted to obtaining the boring rate under most natural conditions in order to 
bring them into relation with the laboratory results observed. A plastic sliding- 
gauge is used for measuring the depth of the holes. A measuring scale is used to 
determine the volumes. The samples are checked at intervals of 12 weeks. 

In the 1st period (in the fall) the minimal boring rate in the field shows an increase 
ranging from 1-3 mm and 0.1-0.25 ml. In the 2nd period (in the winter) l/3 to l/2 of 
that amount is measured and in the 3rd period (in the spring) even lower values are 
obtained as a result of specimens having died due to sedimentation. 

In the laboratory, too, the boring rate decreases from period to period, which is due 
to the fact that the physical condition of the mussels becomes weaker as there is no 
nourishment. In the 1st period, the boring rate yields an increase of 0.4-1.5 mm and 
0.04-0.09 ml. This corresponds perhaps to half the boring rate in proportion to the 
same interval in the field or equals the 2nd period in the field. In the laboratory, the 
boring rate decreases in the 2nd and 3rd period even faster; for a series of smaller 
mussels (20 mm average in holes 8 mm.in diameter), slightly higher values are ob- 
tained in relation to the increase of depth. The increase of volume is nearly the same 
compared with mussels in holes of 12 mm in diameter (Fig. 1). 

Micron-sized and highly porous calcite of the samples BA and BRbl, as well as very 
few pores and no texture showing calcite of the sample V, yield higher values than the 
marble W, having no pores and centimicron-sized grains with distinct twin-laminations, 
caused by pressure, and rounded quartz -grains. The dense calcites HI and H show 
lower values. The marble GM and limestone KK, which is a micron-sized dense 
calcite, richly interspersed with fossils and ferric-oxide-hydrates, yield the lowest 
values. 

The results obtained do not allow a conclusive interpretation as to the texture of 
limestone. Pores, being present, seem to be an obvious factor in facilitating deminer- 

(345) 



346 



PROC. FOURTH EUROP. MALAC. CONGR. 



D 



1,0 mm Ш 0,1 ml 



HIM mm Опт L -ШШ г- mm- 



¡fu У LnJ L^ пГь 



птт— Ш 



Um 



пттт) hmf 1— . i i— 




111 Ь П шПш п 




ВА BRbí W V Ж 11 GM КК 
F R Е I L А N D 12 mm ф 



'J. BRbl,W. П. KK, 
LABOR 12mm 




V. BA, BRblKK t 1 4 
LABOR 8mm f> 



FIG. 1. Boring rates of Lithophaga lithophaga in various types of limestone (see text for types) 
in the field (Freiland) and laboratory (Labor). 

alisation. (Bindings between the grains, which have to be dissolved, are not so strong. 
Dilution at the contact-sheet between mantle and substrate does not take place; on the 
contrary, the enlarged surface leads to a greater degree of demoralization.) The 
micron-sized matrix yields a faster boring rate than the deci- or centi-micron-sized 
matrix. (Smaller grains are dissolved more easily than bigger ones.) How does the 
sample W with its centi-micron-sized matrix and relatively numerous quartz -grains 
fit in here, whereas GM, being marble too, yields the lowest values besides KK? 
Probably the ferric-oxide-hydrates are the cause of the lowest boring rate together 
with the influence of twinned one-crystals and tectonical cracks, which are filled with 
recrystallized calcite. (The significance of the chemical composition is more distinct 
than the matrix/grain/fabric-relation (Kleemann, 1972, dolomite compared with cal- 
cite).) 

The boring rate is not related to the growth rate of the mussels (which is approxi- 
mately 1 decimal less) but equals the boring rate of other organisms in the "Endo- 
lithion" (Riedl, 1966). (Compare with Neumann, 1966 about the boring rate of the sponge, 
С liona lampa.) 

If we take into account the short time of investigation in relation to the age of fully - 
grown mussels (according to the growth rate results the age of mussels was estimated 
up to 80 years (Kleemann, 1972, 1974)) and the fact that their holes are quite often con- 
siderably longer (12 cm), and if we can transfer the problem to the field with varying 
ecological conditions involved, it can be said that the texture of carbonate rock is de- 
cisive for the rate of bio-corrosion which in the samples investigated ranges from 4.3- 
12.9 mm/year. 



KLEEMANN 347 

REFERENCES 

HODGKIN, N. M., 1962, Limestone boring by the mytilid Lithophaga. Veliger, 4: 123- 
129. 

KLEEMANN, К. H., 1972, Der Abbau durch Ätzmuscheln an Kalkküsten. Dissertation 
24.427, 105 p + Bildband, Universität Wien. 

KLEEMANN, К. H., 1974, Der Gesteinsabbau durch Ätzmuscheln an Kalkküsten. 
Oecologia (im Druck). 

NEUMANN, A. C., 1966, Observations on coastal erosion in Bermuda and measure- 
ments of the boring rate of the sponge, Cliona lampa. Limnol. Oceanogr., 11: 
92-108. 

RIEDL, R. J., 1966, Biologie der Meereshöhlen. 632 p, Paul Parey, Hamburg und 
Berlin. 



MALACOLOGIA, 1973, 14: 348 

PROC. FOURTH EUROP. MALAC. CONGR. 

STUDIES ON THE DISTRIBUTION AND ECOLOGY OF LYMNAEA TRUNCATULA 
INTERMEDIATE HOST OF FASCIOLA HEPÁTICA IN PORTUGAL 

Maria de Lourdes Sampaio Xavier, Joäo Fraga deAzevedo and Maria Alice Mattos dos Santos 

Instituto Nacional de Saude "Dr. Ricardo Jorge" Largo 1 de Dezembro, Porto Portugal 

ABSTRACT 

In the present paper we report our findings during 3 years concerning the distribution and population 
dynamics of Lymnaea truncatula, intermediate host of Fasciola hepática in Portugal. 

Contrary to former belief this species proved to be common in fascioliasis areas, mainly in the north of 
the country, where we found not only the highest rate of infection in animals, but also a continuous increase 
in the number of human cases. The initial failure to find this species in the mentioned areas has to be 
attributed to the minute size of this amphibious snail in its various habitats and to the insufficient know- 
ledge of these habitats and snail populations dynamics. 

This is particularly true for the provinces of Alentejo and Algarve (south part of Portugal), where the 
general ecological circumstances (especially the climate) are unfavourable for the development of fascio- 
liasis, though it occurs there in some restricted areas where the microclimate is favourable to the devel- 
opment of Lymnaea truncatula. 



MALACOLOGIA, 1973, 14: 348 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE ROLE OF TEMPERATURE IN THE ECOLOGY AND DISTRIBUTION 
OF THE SNAIL, LYMNAEA STAGNALIS 

Henry van der Schalie and Elmer G. Berry 

Museum of Zoology, The University of Michigan, Ann Arbor, Michigan, U.S.A. 

ABSTRACT 

Forty or 50 years ago the large circumpolar pond snail, Lymnaea stagnalis, was common in southern 
Michigan. This species has now disappeared throughout the southern half of this state. It was used 
extensively for studies in parasitology, genetics and functional anatomy. Recent laboratory studies, designed 
to stress this snail at various temperatures to measure differences in growth and reproduction, indicate 
that it may be quite sensitive to heat budgets. The data appear to indicate that this sensitivity may be 
responsible for its disappearance from lower southern Michigan and explain the shrinking of its present 
range to the upper part of the Lower Peninsula. 



(348) 



MALACOLOGIA, 1973, 14: 349-354 

PROC. FOURTH EUROP. MALAC. CONGR. 

WASSERMOLLUSKEN-ZONOSEN IN DEN MOORWALDERN 
ALNION GLUTINOSAE (MALCUIT) DER UNGARISCHEN TIEFEBENE 

Karl Baba 

Zoologischer Lehrstuhl der Pädagogischen Hochschule, Szeged, Ungarn 

Während der letzten Jahre habe ich in einem umgrenzten Areal der Ungarischen 
Tiefebene zwischen Duna und Tisza (im Eupannonicum) die Isolierungsmöglichkeiten 
der Molluskenzönosen nach Vegetationsbeständen studiert. Die Vegetation hat sich 
hier wegen der Wasserablassungen stark verändert. Natürliche Moorwälder gibt 
es hier kaum noch, früher machten diese Waldassoziationen die dominierende Vege- 
tation des Alföld aus. Ich habe mich mit ihnen beschäftigt, weil in ihnen die ursprüng- 
liche Fauna fortlebt. 

Die Molluskenzönosen der Erlen-Eschen-Aschweiden-Moorwälder habe ich, um die 
Abweichungen darzutun, mit den Wasserzönosen wasserbestandener, sandiger Moor- 
wiesen (Molinion coeruleae) verglichen. Nach Ansicht der Phytozönologen stellt 
diese Pflanzenassoziation einen den Moorwäldern vorausgehenden Zustand dar. Weite- 
re, vergleichsweise untersuchte Gewässertypen waren tote Tiszaarme, Erdgruben, 
Natrongewässer und Reisfelder. 

Von jedem der 47 untersuchten Wasserbiotope habe ich mit Hilfe von je zehn 25 cm- 
Quadraten Proben eingeholt und das Material der Sammlungen aufgrund von 11.975 
Individuen mathematisch bewertet. Mit der Ramsay-Pocs' sehen Formel nahm ich 
Artenidentitäts- sowie Dominanz- und Konstanzidentitätsberechnungen vor und kon- 
trollierte sie mit der chi 2 -Signifikanzprobe. Als Wahrscheinlichkeitsniveau der 
Signifikanz wählte ich aufgrund der sich aus der Methode ergebenden theoretischen 
Erwägungen 5%. (pH-Daten siehe an Tabelle 1.) 

Von den Gewässertypen sind nur die toten Tiszaarme ständig mit Wasser versehen. 
Die Moorwälder, mit Ausnahme der Moorwiesen, weichen nicht nur in ihrer Artenzahl 
und der Zusammensetzung ihrer Charakterarten, sondern auch mathematisch in ihrer 
Artenidentität von den einzelnen Sammelstellen anderer Gewässertypen ab. Die 
meisten Arten kamen aus den Moorwäldern und den toten Tiszaarmen (je 37 Arten 
mit 3232 bzw. 5884 Individuen) und die wenigsten (8 bzw. 1 Art) aus Natrongewässern 
und Reisplantagen zum Vorschein. Die einzelnen Gewässertypen bieten für die massen- 
hafte Vermehrung verschiedener Arten optimale Bedingungen und sind daher aufgrund 
ihrer Artenzusammensetzung bzw. ihrer konstanten, dominanten Arten gut ausein- 
anderzuhalten. In den Moorwäldern und toten Tiszaarmen fand ich nur eine gemeinsame 
konstant -dominante Art: die Bühynia tentaculata (wegen ihrer Eventualität in die 
Tabelle nicht aufgenommen (Tabelle 1)). 

Zwischen den Zönosen der Moorwiesen und Moorwälder besteht eine Artenidentität, 
dies zeigen auch die 6 gemeinsamen konstantdominanten Arten. Beachtenswert ist 
dies, weil zwischen den Pflanzenassoziationen der Molinion coeruleae- und Alnion 
glutinosae- Bestände auch geobotanische Sukzessionszusammenhänge bestehen. 

Die Ursache für die Unterschiede zwischen den Gewässertypen bzgl. Artenzusam- 
mensetzung und Individuenzahl erblicke ich - da es sich um weitverbreitete Arten 
handelt - in der abweichenden Nahrungszusammensetzung (die von der Zusammen- 
setzung und dem Zustand der Vegetation und dem Wasser -pH abhängt). 

Den Unterschied zwischen den Wassertypen der Moorwälder und der ebenfalls 
artenreichen toten Flussarme zeigt der Umstand, dass aus den Moorwäldern mehrere 
konstante, Detritus fressende Schneckenarten und 12 Muschelarten zum Vorschein 
kamen, während in den toten Armen die Pflanzenfresser dominieren. Die gefundenen 

(349) 



350 PROC. FOURTH EUROP. MALAC. CONGR. 

Muschelarten bilden in den Moorwäldern 32% der Gesamtindividuenzahl und in den 
toten Armen nur 1%. 

Nur aus den Moorwäldern kamen Segmentina nitida f. distiquenda und Musculium 
lacustre f. hungaricum zum Vorschein. Den grösseren Anteil der Moorwälder- 
Mollusken (24=42%) machen wärmebeanspruchende oder wärmetolerierende Tiere mit 
weiten Toleranzgrenzen aus. Wegen der wechselnden Wassertiefe und der durch die 
Beschattung seitens der Bäume temperaturmässig aufgeteilten, gegliederten Wasser- 
fläche leben hier auch einige in Ungarn heute schon seltene Arten mit engen Toleranz- 
grenzen, wie z.B. Valvata naticina, Bithynia leachi, Bathyomphalus contortus, Pisi- 
dium supinum und P. milium. Die Molluskenarten der Moorwälder kommen - entgegen 
anderen Gewässern - nicht nur in den Uferregionen massenhaft vor. 

Für die quantitativen Verhältnisse ist charakteristisch, dassinden toten Flussarmen 
die Individuenzahl der konstanten Arten ein Mehrfaches jener der übrigen Arten 
beträgt, während in den Moorwäldern die quantitativen Verhältnisse der konstant- 
dominanten Arten ausgeglichener sind. 

Typisch für die Struktur der Zönosen in den Moorwäldern ist, dass ihre Artenzahl 
an wasserarmen Stellen 10-11 und an wasserreichen 21-24 beträgt. Die Gesamtindi- 
viduenzahl in den Aschweidenbeständen beträgt 148-175, in den Klimaxwäldern 271-460 
(einmal sogar 1036), in den Moorwäldern 11; auf den Moorwiesen können 6 Arten - 
entsprechend dem Zustande der Pflanzensukzessionen konstant -dominant werden 
(Tabelle 1.). Charakteristish für die Moorwälder ist, dass in ihnen auch mehr als 
zwei Arten absolute Konstanz erreichen können. Hier fehlen die Arten mit mittlerer 
Konstanz (50-60%). Die grosse Zahl der über eine hohe Charakteristik verfügenden 
Arten zeigt, ähnlich wie bei den Landzönosen beobachtet, die Prozesse der Umwandlung 
der Zönosen an. In den wasserreichen Moorwäldern zeigt die hohe Zahl der jugend- 
lichen Individuen im Verhältnis zur Gesamtindividuenzahl (69-82%) die Stabilität der 
Zönosen an. 

Die Basis meiner Untersuchungen bildeten die Pflanzenassoziationen und die ihnen 
entsprechenden elementaren Molluskenzönosen, die Synusien. Die Molluskensynusie- 
typen sind in Pflanzenassoziationsserien nach Pflanzenassoziationen im folgenden 
angegeben. In Klammern sind nach den Namen der Molluskensynusien die ebenfalls 
charakteristischen subkonstant-subdominanten Arten angeführt. 

Reisplantagen 

Physa fontinalis - Radix peregra f. ovata, Physa fontinalis - Radix peregra f. 
ovata - Gyraulus albus 

Erdgruben entlang der Tisza 

Planorbarius corneus, Planorbarius corneus - Lymnaea stagnalis (Musculium 
lacustre) Planorbarius corneus (Lymnaea stagnalis), Lithoglyphus naticoides - 
Lymnaea stagnalis, Radix peregra f. ovata (Lymnaea stagnalis, Planorbis plan- 
orbis) 

Natrongewässer 

Anisus spirorbis 

Pflanzen-Assoziationen der toten Tiszaarme 

a) Hydrocharietalis Tx. et Prsg. Hydrochari-Stratiotetum fac: Ceratophylletosum 
demersi Kárpáti: Gyraulus albus - Planorbarius corneus (Armiger crista, Lymnaea 
stagnalis), 

b) Potametalia W. Koch. Myriophyllo - Potametum myriophylletosum spicati Soó: 
Bithynia tentaculata (Radix peregra f. ovata). Nymphaeetum albo-luteae nymph- 



BABA 



351 



TABELLE 1. Liste der konstant-dominanten Arten. 



i 

pH 5,8 

6,5-5,7 



2 

6,5-8,5 



5 
7,5-a,5 



4 

7,5-9 



5 
7,5-8 



6 
6,5-7 



7. 



V, 



m 



ш 



ш 



IB 



Viviparus contée tus (Millet) 
Viviparus viviparus (L.) 
Viviparus acerosus Bourguignat 
Valvata cristata O. F. Müll. 
Valvata pule he lia Studer 
Valvata piscinalis (O.F. МШ1.) 
Valvata naticina Menke 

8. Lithoglyphus naticoides (C. Pfeüfer) 

9. Bithynia tentaculata (L.) 

10. Bithynia leachi (Sheppard) 

11. Aplexa hypnorum (L.) 

12. Physa fontinalis (L.) 

13. Physa acuta (Drap.) 

14. Galba truncatula O.F. МШ1. 

15. Stagnicola palustris (O.F. MU11.) 

16. Radix auricularia auricularia (L.) 

17. Radix peregra (O.F. MU11.) 
Radix peregra f. ovata (Drap.) 

18. Radix ampia (Hartm.) 

19. Lymnaea stagnalis (L.) 

20. Planorbis planorbis (L.) 

21. Planorbis carinatus (O.F. МШ1.) 

22. Anisus septemgyratus (Rossm.) 

23. Anisus leucostomus (Millet) 

24. Anisus spirorbis (L.) 

25. Anisus vortex (L.) + 

26. Anisus vorticulus charteus (Held) + 

27. Bathyomphalus contortus (L.) + 

28. Gyraulus albus (O.F. Müll.) + 

29. Gyraulus laevis (Alder) + 

30. Armiger crista (L.) + 

31. Segmentina nitida (O.F. МШ1.) 
Segmentina nitida f. distiquenda Gr edler |+] 

32. Hippeutis complanatus (L.) + 

33. Planorbarius corneus (L.) + 

34. Acroloxus lacustric (L.) + 

35. Gundlachia Uni sp. (Wouteri) 

36. Unio tumidus f. decurvatus (Rossm.) 

37. Anodonta cygnea f. zellensis (Gmelin) 

38. Spaerium corneum (L.) + 

39. Musculium lacustre (O.F. Müll.) 
Musculium lacustre f. hungaricum 

40. Pisidium henslowanum (Sheppard) 

41. Pisidium supinum (A. Schmidt) 

42. Pisidium milium (Held) 

43. Pisidium subtruncatum (Malm.) 

44. Pisidium nitidum (Jenyns) 

45. Pisidium pulchellum (Jenyns) 

46. Pisidium personatum (Malm.) 

47. Pisidium obtusale (C. Pfeiff.) 

48. Pisidium casertanum (Poli) 

49. Pisidium hibernicum (Westerlund) 

Artenzahl 



Hazay 



m 



57 



Dominante konstante Arten 



a 



э 



ш 



+ 


s 


ш 




m 


+ 




a 


s 


a 


+ 
+ 


+ 


fi 


+ 





ш 



+ 

s 

+ 

в 

+ 

+ 
+ 

3 



IB 



к 



25 



Legenda: 1, Alnion glutinosae (Malcuit); 2, Toter Tiszaarm; 3, Erdgruben entlang der Tisza; 
4, Natrongewässer; 5, Reisplantagen; 6, Molinion coeruleae W. Koch 



352 PROC. FOURTH EUROP. MALAC. CONGR. 

aetosum Kárpáti: Sphaerium corneum - Viviparus viviparus. Nymphaeetum albo- 
lutaea Nowinski: Gyraulus albus - Gyraulus crista (Acroloxus lacustris). Trapetum 
natantis Müller & Görs: Hippeutis complanatus - Acroloxus lacustris {Radix 
peregrai. ovata). Nymphaeetum albo-luteae Trapa natansSoó: Viviparus viviparus 
- Planorbarius corneus. 

c) Phragmitetalia W '. Koch. Scirpo-Phragmitetum medioeuropaeumTx.ia.c: typheto- 
sum, (Potamogetón crispus): Gyraulus cristata, Physa fontinalis - Radix ampia, 
Radix peregra f. ovata, Planorbarius corneus, Lymnaea stagnalis - Radix ampia, 
Lymnaea stagnalis - Planorbarius corneus. 

d) Komplex-Pflanzen-Assoziation Hydrochari - Stratiotetum stratioietosum (Langen- 
donck), Nymphaeetum albo-luteae Nowinski Komplex: Gundlachia wouteri? - Acro- 
loxus lacustris (Gyraulus albus). Nymphaeetum albo-luteae Nowinski fac: Syum 
latifolium, Myriophyllo-Potametum Soó Komplex: Gyraulus albus - Gyraulus 
crista (Acroloxus lacustris - Bithynia tentaculata) . Caricetum elatae W. Koch, 
Nymphaeetum albo-lutaea Nowinski fac. \ Lemno- Utricular ietum Komplex: Gyraulus 
albus - Galba truncatula - Gyraulus crista (Bithynia tentaculata, Hippeutis com- 
planatus). Scirpo-Phragmitetum schoenophetosum Soó Nymphoidetum peltatae 
(Allorge) Komplex: Acroloxus lacustris - Planorbarius corneus. Scirpo-Phrag- 
mitetum W. Koch, Nymphaeetum albo-luteae Nowinski Komplex: Gyraulus albus - 
Gyraulus crista. Scirpo-Phragmitetum-typhoetosum angustifoliae Soó, Nymphaee- 
tum albo-luteae Nowinski Komplex: Gyraulus crista - Acroloxus lacustris. Scirpo 
Phragmitetum sparganietosum Soó, Nymphaeetum albo-luteae Nowinski Komplex: 
Valvata piscinalis - Gyraulus albus -Acroloxus lacustris. 

Sandige Moorwiesen und Moorwälder 

Molinion coerulae (Malcuit): Valvata cristata - Bithynia tentaculata, Valvata 
cristata - Planorbis planorbis. 

Calamagostri - Salicetum cinereae Soó & Zólyomi fac: Carex elongatae: 
Bithynia tentaculata - Valvata cristata (Sphaerium corneum), fac: Phragmites: 
Sphaerium corneum - Bithynia tentaculata (Planorbarius corneus), fac: Carex 
acutiformis: Segmentina nitida - Planorbis planorbis (Anisus septemgyratus), 
fac: Lastea the lypteris: Segmentina nitida - Planorbis planorbis - Anisus septem- 
gyratus (Bithynia tentaculata, Valvata cristata). 

Fraxino pannonicae - Alnetum hungaricum Soó & Komlósi fac: Carex acuti- 
formis, C. riparia, С. elatae: Bithynia tentaculata - Valvata cristata, fac: Hotton- 
ietosum, Carex remota, Urtica dioica: Galba truncatula - Pisidium obtusale 
(Pisidium casertanum, Valvata cristata, Stagnicola palustris). 

Die im Abschnitt "Sandige Moorwiesen und Moorwälder" angeführten Synusien 
gehören dem Valvata cristata - Bithynia tentaculata - Pisidium obtusale - Mala- 
kosozion an. 

Fraxino pannonicae - Alnetum hungaricum Soó & Komlódi fac Dryopteris 
Konsozion: Anisus spirorbis - Aplexa hypnorum (Viviparus contectus). 

Ein von den übrigen abweichendes, montanes Synusium am nördlichen Rande 
der Ungarischen Tiefebene (Alföld): Dryopteridi - Alnetum Klika. fac: Thelyp- 
teridetosum palustris: Pisidium casertanum - P. milium - P. hibernicum (Anisus 
spirorbis, Segmentina nitida). 
Obzwar die einzelnen Moorwälder sich in verschiedenen Phasen der Vegetations- 
sukzession befinden, besteht zwischen ihnen doch eine starke, 56-65%-ige, Konstanz- 
und Dominanzidentität. Die Zusammengehörigkeit der Zönosen ist auch malakozönolo- 
gisch nachweisbar. Die häufigsten Charakterarten der vom Gesichtspunkte der 
Sukzession jüngeren Aschweidenbestände sind, ähnlich wie im Falle der Moorwiesen, 
vorwiegend Valvata cristata, Bithynia tentaculata, Planorbis planorbis und Segmentina 



BABA 353 

nitida. In den Klimax-Erlen-Eschen-Moorwäldern erscheinen neben den Scheckearten 
auch Pisidium obtusale, Pisidium casertanum oder andere konstant -dominante Muschel- 
arten. 

KONKLUSION 

Die in eine Sukzessionsreihe einfügbaren Biotope, von den Moorwiesen bis zu den 
Moorwäldern, unterscheiden sich strukturell - und dementsprechend aufgrund ihrer 
Identitätsziffern auch nach der Zusammensetzung ihrer Sammelstellen -mathematisch 
von anderen Gewässertypen. 

Die von den Moorwiesen bis zu den Moorwäldern reichende Sukzessionsreihe lässt 
sich in ein in Richtung der Sukzession zeigendes Sozion {Valvata cristata - Bithynia 
tentaculata - Pisidium obtusale) und in ein wegen des Austrocknens auf die Reg- 
ression hindeutendes Konsozion (Anisus spirorbis - Aplexa hypnorum) aufteilen. Die 
die Sukzessionsreihe zusammenfassende zönologische Kategorie, das Sozion, ist im 
Gegensatz zu anderen Gewässertypen mit der Gesamtheit der gemeinsam vorkommen- 
den hochcharakteristischen Arten zu kennzeichnen (Charakterarten). Diese Arten 
sind: Valvata cristata, Planorbis planorbis, Anisus septemgyratus, Segmentina nitida, 
Pisidium obtusale, Pisidium casertanum und die hochfidelitative Viviparus contectus, 
bzw. Anisus vorticulus. 

Die Untersuchung der Pflanz enzönosen und der Molluskenzönosen dürfte auch bei 
der Bewertung der Molluskenperiode des Pleistozän verwertbar sein. 

BIBLIOGRAPHIE 

BALOGH, J., 1958, Lebensgemeinschaften der Landtiere. Akad. Kiadó, Berlin-Buda- 
pest. 
BABA, K., 1967, Malakozönologische Zonenuntersuchungen im toten Tiszaarm bei 

Szikra. Tiscia, 41-55. 
BABA, К., 1969, Die Malakozönologie einiger Moorwälder im Alföld. Opuse. Zool., 

Budapest, 9, 1: 71-76. 
BABA, К., 1969, Zönologische Untersuchungen der an der Flussbettkante der Tisza 

und ihrer Nebenflüsse lebenden Schnecken. Tiscia, 5: 107-119. 
FRÖMMING, E., 1956, Biologie der mitteleuropäischen Süsswasserschnecken. Duncker 

& Humblot, Berlin. 
HORVÁTH, A., 1954, Az alföldi lápok puhatestüiröl es az Alföld változásairól. Állatt. 

Közl., 44: 63-70. 
PÓCS, T., 1966, Statisztikus matematikai módszer novénytársulások elhatárolására. 

Egri Tanárképzo Föisk. Füz., 4: 441-454. 
SOÓ, R., 1964, A magyar flora és vegetáció rendszertani-növenyföldrajzi kézikony ve. 1. 

Akad. Kiadó, Budapest. 

SUMMARY 

WATER MOLLUSCA COENOSES IN MARSH-WOODS: 
ALNION GLUTINOSAE (MALCUIT) Ш THE GREAT HUNGARIAN PLAIN 

The water Mollusca coenoses (w.m.c.) of Alnus, Fraxinus and Salix cinerea in 
marsh-woods (m.w.), sandy-soiled marsh-meadows (m.m.) and other water types 
found now but in traces in the territory between the Danube and Tisza are compared 
and their separability according to the vegetation is investigated. The coenological 
collections are evaluated with a mathematical method. The calculations are checked 



354 PROC. FOURTH EUROP. MALAC. CONGR. 

with significance test chi . The constant, dominant species change according to water 
types and states of plant succession (Table 1). The molluscan synusia of plant associ- 
ations are given in the text. In m.w., not so as in other water types, more than 2 
species can be absolutely constant. Besides the water snails fed mainly on detritus, 
the dwarf shells form 32% of the total individual number, while in other waters their 
number is not even as high as 1%. The w.m.c. of m.w. and m.m. significantly differ 
from other water types in species constancy and dominance identity, having at the 
same time between themselves a high degree of species identity. Common constant 
species: 6. The m.w. and m.m. are, according to the plant coenologues, in a connec- 
tion of succession. 



MALACOLOGIA, 1973, 14: 355-370 

PROC. FOURTH EUROP. MALAC. CONGR. 
SOME WOODLAND MOLLUSC FAUNAS FROM SOUTHERN ENGLAND 

R. A. D. Cameron 
Department of Biological Sciences, Portsmouth Polytechnic, Portsmouth, England 

INTRODUCTION 

The only comprehensive account of the habitats of British terrestrial molluscs is 
that of Boycott (1934). His approach, for the most part, was to attempt to define the 
range of habitats occupied by each species, and to relate this to environmental vari- 
ables. Many of the British species (nearly half the total), proved to have very wide 
ranges of habitat. As Boycott himself realized, the broadness of many habitat-ranges 
was the result of geographical variation in habitat preference within Britain. Recent 
studies (Cameron, 1970; Cameron & Palles-Clark, 1971) confirm this, showing that 
the habitats occupied by one species may change considerably over short distances 
(10-50 km) as a response to quite small changes in climate. 

Work in some other European countries, starting with the pioneer work of Favre 
(1927), has a different approach: determining the number and variety of species found 
in particular environments (Waiden, 1965). This approach, especially when conducted 
in a quantitative manner, has yielded interesting results (Ant, 1969; Körnig, 1966; 
Waiden, 1955; Wareborn, 1969), suggesting the existence of characteristic molluscan 
assemblages associated with various habitats. This study follows the pattern of these 
investigations, but in a very restricted range of habitats in a small, zoogeographically 
homogenous area: deciduous woodlands on the chalk hills of Sussex and Hampshire. 

THE AREA AND HABITATS STUDIED 

The map (Fig. 1) shows the area and localities sampled. All sites are on the South 
Downs, a range of Cretaceous chalk hills rising gently from the coastal plain to an 
east-west scarp 200-250 m a.s.l. The north-facing slopes of the scarp are steep 
(usually ca. 30°); those on the south-facing dip slopes are varied, and there are 
plateau areas with very gentle slopes. 

The climate is mild by British standards. Annual rainfall varies from 29 inches 
(725 mm) on the lower southern slopes to 39 inches (975 mm) on some parts of the 
scarp. Mean monthly temperatures range from 17.0°C in July to 5.5°C in January 
(Meteorological Office, 1952). 

Substantial parts of the South Downs are wooded, but many woods, especially on the 
dip slopes, are recent plantations, mostly of conifers. The mature deciduous woods 
are usually dominated by beech {Fagas sylvatica), which is sometimes the sole canopy 
species, but ash (Fraxinus excelsior) is also frequent and is a co-dominant with beech 
in some woods. Oaks (Quercus spp.), sycamore (Acer pseudoplatanus) and various 
introduced conifers occur sporadically. Many woods lack a secondary layer of woody 
plants; where it is present it is usually of yew (Taxus baccata) and occasionally of 
hazel (Corylus avellana), hawthorn (Crataegus spp.) or elder (Sambucus nigra). 

In most sites, the tree canopy is very dense and ground cover scanty, especially 
in pure beechwoods on the scarp, where 90% or more of the ground may be devoid of 
vegetation. In all the scarp woodlands, and in many of the others, the most abundant 
herb is dog's mercury (Mercurialis perennis) with Solomon's seal (Polygonatum 
multiflorum) and wild garlic (Allium ursinum) being locally abundant on wetter slopes. 

(355) 



356 PROC. FOURTH EUROP. MALAC. CONGR. 

On the acid soils of the gentlest slopes, blackberry (Rubus fruticosus agg.) usually 
dominates. Small clearings and other recently disturbed areas are often covered with 
stinging nettle (Urtica dioica) or willowherbs (Epilobium and Chamaerion spp.). 

On the scarp, steepness and lack of herbaceous cover result in unstable soil surfaces; 
the soil is usually shallow and there is much chalk debris at the surface. All measure- 
ments of soil pH at the surface in scarp sites were greater than 7.0. On the gentler 
slopes the soil is deeper; brown earth soils with no chalk visible at the surface. In 
a few sites, thin layers of clay overlie the chalk. 

Due perhaps to the softness of the rock, there are no natural crags or boulders, 
even on the steepest slopes. The porosity of the rock tends to minimize both surface 
run-off and waterlogging, and none of the sites are very wet. 

All woods in the area are to some extent man-made and are subject to some dis- 
turbance in the form of forestry activities and the clearing of paths and rides for 
shooting and rearing pheasants. A few of the woods on the gentle slopes show signs of 
coppicing. These activities are more frequent on the dip slopes, and many sites on the 
scarp have not been disturbed for some time - trees have been allowed to die and fall, 
with no signs of thinning or clearing. Forestry records (Brown, 1953) indicate that 
even these woods are planted (at least in part), and it seems doubtful if beech is the 
natural dominant of any British woodlands (Godwin, 1956; Pennington, 1969). 

METHODS 

For each site, an area of ca. 1000m 2 was chosen in a wood so that (a) it did not 
include any wood-edge, and (b) it was covered, as far as possible, by a canopy of 
mature trees. In each such area, molluscs were searched for and collected by hand, 
the search lasting for 1 hour in each case. In addition, small amounts of soil and litter 
were taken from over each area, to a volume of about 1.5 1, and removed for examina- 
tion in the laboratory. A colourimetric determination of pH was made on soil from 
the top 1 cm at each site, together with a brief description of the vegetation. 

Material brought back to the laboratory was dried and passed through a series of 
sieves, the smallest mesh being 0.5 mm. Any material passing through this was 
discarded and the remainder as searched for molluscs with the aid of a binocular 
microscope. 

The combination of these 2 methods of collecting yields consistent and repeatable 
qualitative results for snails, but quantitiative estimates of abundance based on 
searching in the field are unreliable. This method is retained in order to ensure 
adequate representation of the larger and less populous species. The results for 
slugs are much less satisfactory, and it is clear that only a small proportion of the 
slug fauna has been discovered in some cases (Wareborn, 1969). Nearly all samples 
were made in dry weather, it being too dark inside some woods to search effectively 
during rain. The samples were made between June and September (so that plant- 
cover could be assessed at the time of sampling), in 1968, 1969 and 1970. 

RESULTS 

Table 1 shows shows the site characteristics of each sample made. Table 2 lists 
the mollusc fauna of each site. It is evident from Table 2 that there are differences 
between sites both in numbers of species found and in species composition. The 
analysis which follows refers only to snails; the slugs are discussed briefly at the end. 

Variation in number of species per site 

Table 3 shows the mean number of species per site in categories defined by topo- 
graphy, soil pH, and plant cover. Samples from the scarp have a higher mean than 



CAMERON 



357 



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vM- 1 -^ =scarps 



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FIG. 1. A map showing the study area and sample sites. The British Ordnance Survey 10 km 
grid is shown in the margins. 



TABLE 1. Habitat characteristics of the samples mentioned in the text. 



Scarp Samples: 



1 - 24. 



Bare ground 90%+: 



2,4,8,10,13,14,16,18,19,21. 



Intermediate 

(50-90% bare ground): 1,3,9,12,15,17,20,22,23. 

Covered 

(0-50% bare ground): 5,6,7,11,24. 

Rubus fruticosus present: 11,15. 



Non scarp Samples : 



25-44. 



Soil pH: 7.0+ : 
6.0- 7.0 : 
5.0- 6.0 : 



25,26,27,28,30. 

29,31,32,33,34,35,36,37,38,39. 

40,41,42,43,44. 



Rubus fruticosus present 2 9,35,36,38,39,40,41 .42.43.44. 



358 



PROC. FOURTH EUROP. MALAC. CONGR. 



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360 



PROC. FOURTH EUROP. MALAC. CONGR. 



TABLE 3. Variation in mean number of species of snail per site with topography, soil pH 
and vegetation cover at ground level. 



Category of 


Mean number of species 


Number of sites 


Site 


per site 




Scarp 9ites 


19.7 


10* 


with bare ground 






Intermediate scarp 


18.4 


9 


sites (10-50% cover) 






Covered scarp sites 


16.6 


5* 


(50-100% cover) 






All Scarp sites 


18.6 


24** 


Non-scarp sites 


15.8 


5** 


(a)pH 7.0+ 






(b)pH 6.0-7.0 


12.9 


10** 


(c)pH 5.0-6.0 


8.2 


5** 



**all significantly different from each other at p<0. 05. 
* significantly different, p<0.02, (Wilcoxon, Mann, Whitney test in each case). 

the others, even than those elsewhere with alkaline soils. Within dip-slope samples, 
samples with the highest soil pH values have the highest mean. Within the scarp 
samples, there are smaller differences in mean number of species between sites with 
differing amounts of ground cover. The barest sites have the highest mean, and the 
most covered the lowest. 

The degree of similarity of species composition between sites 

A measure of the similarity in species composition between sites has been obtained 
by calculating a Simple Matching Index (S.M.I.) for each sample with respect to each 
of the others in turn (Sokal & Sneath, 1963). The matrix produced has been reduced 
to a dendrogram (Fig. 2) by successively combining the S.M.I.'s of the most similar 
sites remaining in the matrix (Sokal & Sneath give details of procedure). The S.M.I, 
takes into account similarities between sites produced by absence of a species from 
both, as well as presence in both. If a set of very dissimilar faunas were compared, 
the use of such an index would be misleading, as absence may be caused by a variety 
of different factors. In this case, where a small number of factors appear to be effective 
and the faunas are broadly similar, such an index seems more useful than one based on 
presence alone, since absence of a species from any 2 sites ib likely to relate to 



CAMERON 



361 



lOO-i 



95- 



>- 



90- 



85- 



A 



В 



С 



38 43 41 39 34 33 27 35 7 31 3 17 22 13 2 14 24 5 28 Ю23 25 
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W 



UL 80- 

Ll 

< TS-) 
° 70- 
65- 

60-I 

FIG. 2. A dendrogram showing the levels of affinity connecting the samples , based on the Simple 
Matching Index. 

TABLE 4. Distribution of samples from each faunal group (А, В, C) with re- 
spect to environmental factors mentioned in the text. 

Groups ABC 



Number of sites 



11 



24 



Scarp samples 
Non-scarp samples 



20 
4 



Scarp samples: 

(a) bare ground 

(b) Intermediate 

(c) Covered 






10 


1 


8 


3 


2 



Mean pH of non-scarp 
samples 



5.7 



6.5 



7.0 



Samples with Rubus 



362 



PROC. FOURTH EUROP. MALAC. CONGR, 



TABLE 5. 



Frequency of occurrence (%) of each species in each faunal group: 1, 
species restricted to Group C; 2, species restricted to group A; 3, 
"Universal" species; 4, Species more frequent in В and С than A; 
5, Species most frequent in A; 6, rare species (less than 4 occurrences). 





GROUPS 


SPECIES 


A 


в 


С 


1 Acicula fusca 


11 





83 


Clausula rolphll 





9 


75 


Hellcodonta obvoluta 








50 


Hellclgona lapicida 








18 


Helix as persa 





27 


88 


Punctum pygmaeum 








54 


2 Vitrea crystallina 


55 





4 


Retine lia radlatula 


66 








3 Marpessa lamlnata 


77 


100 


100 


Discus rotundatus 


100 


100 


100 


Oxychllus alllarlus 


100 


100 


83 


Retlnella nltldula 


77 


81 


100 


4 Carychlum trldentatum 


44 


100 


100 


Cochllcopa lubrica agg 


33 


63 


71 


Clausula bldentata 


11 


90 


71 


Cepaea hortensis 


11 


54 


62 


Cepaea nemoralls 


33 


45 


54 


Vitrea contracta 


11 


81 


96 


Oxychllus cellarlus 


55 


90 


79 


Oxychllus helvetlcus 


11 





13 


Retlnella pura 


33 


90 


92 


Pomatlas elegans 


33 


54 


100 


Acanthlnula aculeata 


11 


18 


29 


Ena obscura 





45 


75 


Hygromla hispida 


33 


54 


67 


Hygromla strlolata 


44 


27 


62 


Vitrina pelluclda 


33 


81 


58 


5 Euconulus fulvus 


77 


63 


54 


6 Ablda sécale 








8 


Cecllloldes aclcula 





18 


4 


Arlanta arbustorum 








12 


Hygromla subrufescens 





9 





Monacha cantlana 


11 





4 



the same factor in each case. 

For further analysis, the sites have been split into 3 large groups, an arbitrary 
level of affinity being chosen for the purpose (70%). Three samples are not connected 
to others at this level. Samples 34 and 40 are clearly closer to Group A (Fig. 2) than 
to the others. Sample 8 is related to Groups В and C. Inspection of individual S.M.I.'s 
indicate closer affinities with sites in Group С than Group B, and it is assigned to the 
former group. 

Table 4 shows the properties of sites in each group in relation to topography, soil 
pH and plant cover. It is evident from the table that each group of sites has distinctive 



CAMERON 
TABLE 5a. Number of occurrences of slug species in each faunal group. 



363 





A 


В 


С 


Species 








Avion intermedius 





3 


1 


*Arion circumscriptus 


3 


3 


4 


Avion hortensis 


2 


1 


13 


Avion subfuscus 


2 


2 


5 


*Avion atev 


1 


3 


П 


Milax sowevbyi 








1 


Limax maximus 


2 


4 


10 


Limax cineveonigev 





2 


9 


Limax mavginatus 


3 


2 


9 


Agviolimax veticulatus 





3 


1 



*Aggregate species not segregated by dissection (Ellis, 1969). 

habitat features; similar snail faunas tend to occur in sites with similar environments. 
The number of sites and the amount of environmental information is too small to 
attempt explanation of small groups of sites with closer affinities. 

Group A sites are characteristically acid; the commonest herb recorded is Rubus 
fvuticosus agg. Group С sites, the richest in species, are nearly all on the scarp, 
and nearly all alkaline. Scarp sites with bare ground predominate. The Group В sites 
are intermediate in character. 

The occurrence of individual species 

The 3 affinity groups described above are strongly related to the various habitat 
categories described earlier. This implies that variation in mean species number 
between categories is, at least in part, the consequence of the same species being 
eliminated in each site. This can be examined by comparing the frequency of occur- 
rence of each species in each group (Table 5). Inspection of the table shows that this 
is indeed the case. Some species occur in almost all sites in all groups; a larger 
number are almost exclusive to Group С and. 2 to Group A. Most of the rest are more 
frequent in В and С than in A, but the magnitude of the difference varies. Although a 
few species reach their highest frequency in Group B, there is no real evidence that 
any species is particularly characteristic of that group. 

Slugs (Table 5) 

The general trend seen amongst snails, for species to be most frequent in Group C, 
is present also in the slugs. Group A has the least species recorded from it, and those 
that do occur tend to be less frequent than in Group C. Avion hovtensis and Limax 
cineveonigev in particular are more frequent in Group С than elsewhere. 



364 PROC. FOURTH EUROP. MALAC. CONGR. 

DISCUSSION 
Character of the Faunas studied 
The influence of soil pH 

The association of snail-faunas rich in individuals and species with alkaline soils 
is well known (Atkins & Lebour, 1923; Boycott, 1934; Valovirta, 1968). The relation- 
ship is not direct, available calcium in the soil being more specific (Burch, 1955). 
Calcium available in leaf litter may be much more than would be inferred from soil 
pH, especially in acid soils (Wareborn, 1969). No measurement of available calcium 
was made in this study, but the very direct contribution made by underlying calcareous 
rock to conditions at the soil surface means that pH is probably a reasonable assess- 
ment of calcium availability. Soil reaction may also be indicative of certain structural 
properties of soil important to molluscs (Lozek, 1962). 

The reduction in average numbers of species with increasing acidity is marked, the 
more noticeably since all sites have mull soils with no perennial accumulation of 
litter. Fall-off in species numbers with acidity is not so rapid in some Pyrenean 
woods (Cameron, unpubl.) and many woodlands on acid soils have more species than 
are recorded here (Favre, 1927; Boycott, 1934; Valovirta, 1968; Wareborn, 1969), 
even though many of those studied are much further north. 

As might be expected (Boycott, 1934), many of the species which vanish or are much 
reduced in Group A are large, thick shelled species usually restricted to calcareous 
districts- Pomatias elegans, Helicigona lapicida and Helix aspersa. Some species on 
the edge of their range in Britain are also known to be calcicole there:- Helicodonta 
obvoluta (Cameron, 1972), Clausilia rolphii (Boycott, 1934) and A b ida sécale (Kerney, 
1962). Other snails regarded as mildly calcicole also show varying reductions in 
occurrence: Cepaea hortensis and C. nemoralis, Ena obscura, Carychium tridentatum 
and Acanthinula aculeata (Boycott, 1934). The reduction of Vitrea contracta in Group 
A is paralleled by an increase in its congener V. crystallina - the change may relate 
to dampness rather than soil acidity (Kuiper, 1964). 

There are, however, a number of species whose occurrence is not explained by 
reference to soil pH. Punctum pygmaeum and Clausilia bidentata are both more 
tolerant of acid conditions than many other species showing less reduction in Group A 
(Boycott, 1934), while Marpessa laminata, one of the most frequent species in all 
groups, is more calcicole than many species which diminish considerably in Group A. 
The other dominant species in Group A, however, including Retinella radiatula, Vitrea 
crystallina and Euconulus fulvus are all species tolerant of mildly acid conditions 
(Boycott, 1934). Amongst slugs only Arion hortensis is thought to favour calcareous 
soils (Boycott, 1934); it does reach its highest frequency in Group C. 

The nature of the molluscan faunas 

Study of the groups of sites produced by analysis of the S.M.I, matrix shows that 
particular sets of environmental conditions tend to contain specific molluscan faunas. 
Inspection of Wareborn's (1969) and Kornig's (1966) results, also from woods, suggests 
a similar conclusion. Such a conclusion would be expected on general ecological 
principles, but in the circumstances of this study the result has a special significance. 
All sites here have suffered from human interference, and in such sites one might 
expect the fauna to reflect accidents of recolonization or recent destruction. The 
high levels of affinity, especially for Group С sites, suggest that they have reached an 
approximately natural state in which all available niches have been filled by the 
appropriate species; disturbance is no longer the main determinant of faunal composi- 
tion (but see below). 



CAMERON 365 

The difference between the 3 groups are such that A and В do not have their own 
characteristic species, but are merely impoverished versions of C. Of the 33 species 
of snail found in the study, only 2 are missing from Group С (Table 6): Retinella 
radiatula is frequent in A sites; Hygromia subrufescens occurs once only (in a Group 
В site). Of the 5 dominant (occurrence 75%+-) species in Group A 4 are also dominant 
in Groups В and C, and the remaining 1, Euconulus fulvus, is not uncommon in them. 
Only Vitrea crystallina and R. radiatula are at all specific to Group A. In other studies 
of woodland molluscs over a range of soil acidity, there are often more signs of a 
distinctive acid soil fauna, especially when density as well as occurrence is considered 
(Waiden, 1955; Valovirta, 1968; Wareborn, 1969). 

The effect of disturbance on the faunas 

The woods of the dip-slopes show most signs of disturbance. The effects of this 
disturbance are hostile to snails; compaction of the soil and removal of timber so 
that little is left to rot are possibly the worst (Boycott, 1934). The presence of 
naturally fallen timber on the scarp sites is a good indicator for Helicodonta obvoluta 
(Cameron, 1972), a species known to be adversely affected by disturbance. Of the 
other species regarded by Boycott as anthropophobes, Acicula fusca, Limax cinéreo- 
niger and Hygromia subrufescens occur here, the last only once, but the other anthro- 
pophobe slug, Limax tenellus (Müll) is apparently absent. A. fusca is here restricted 
to Group С sites, but this cannot be attributed to soil pH, as it can occur in undisturbed 
acid woodlands (e.g., Tore Woods, Kerry; Boycott, 1934). The same argument applies 
to L. cinereoniger. Since there is some evidence of plantation and management all 
over this area, the idea that L. einer eoniger is restricted to primaeval forest (Boycott, 
1934; Quick, 1949) is not entirely correct. 

Inspection of Table 6 shows that there is a much higher proportion of "rare" 
(occurrence less than 50%) species in Group A than in the others. This could be, in 
part, an artifact due to low population densities of the species concerned, but it 
suggests that the occurrence of many species in Group A is due to accidents of des- 
truction or recolonization. This suggestion runs counter to the argument in the above 
section, and it is possible that S.M.I, is not the most appropriate index of affinity for 
Group A, because absences in common will in fact contribute far more to the intra- 
group indices than presences, unlike the situation within Groups В and C. 

Disturbance could also explain the variation in numbers of species per site in 
scarp woodlands with ground cover. The dense canopy of mature beech trees often 
prevents the development of ground-flora. Dense carpets of Mercurialis perennis 
indicate a higher than average light intensity, which could be caused by thinning. 
Mercurialis itself is certainly no deterrent to snails; many rest and feed on it, and 
some show a strong preference for it in laboratory food trials (Frömming, 1954; 
Grime & Blithe, 1969; Grime, Dearman & McPherson-Stewart, 1968). 

Comparison with other faunas 

Other woodlands in Britain 

There is no systematic account of the faunas of woodland in Britain, but there 
are many accounts of the faunas of individual woods. The most appropriate comparisons 
are with other calcareous woods: from chalk (Ellis, 1942), Jurassic Limestones (Boy- 
cott, 1934; Salisbury, 1946), Carboniferous Limestones (Stratton, 1956; Kerney & 
Fogan, 1969; Cameron, unpubl.), and calcareous tufa in an otherwise acid situation 
(McMillan, 1954). The similarity between these faunas and those on the South Downs 
is considerable. Many of the sites above, however, hold more species than are found 
in any one site on the South Downs, and if non-calcareous woods are considered as 



366 PROC. FOURTH EUROP. MALAC. CONGR. 

well (Boycott, 1934; Stratton, 1951, 1956 and 1964; Langmead, 1949; Lloyd-Evans, 1958), 
the overall list of snails recorded from woodland is much larger than that given here. 
There are a variety of probable reasons for the absence of the extra species. 

Variations in geographical distribution . Lauria anglica, Helix pomatia, Acanthinula 
lamellata, Clausula dubia and Vitrea diaphana are all absent from the whole area 
studied, most being northerly species in Britain (Ellis, 1951; Kerney & Fogan, 1969). 
Ena montana has not been found in the area recently although it used to be there (Boy- 
cott, 1934). Conversely, Helicodonta obvoluta is found only in the study area, and is 
absent from the rest of Britain (Cameron, 1972). 

The occurre nce of cliffs, rocks and open scree. The study area, unlike many of the 
others, lacks natural areas of bare rocks or boulders. Two species often associated 
with rocks occur rarely in the area: Ablda sécale (Kerney, 1962; Long, 1970) and 
Helicigona lapicida (Stratton, 1956). Other rock-loving species found in other woods 
are completely absent -Balea perversa, Lauria cylindracea and Pyramidula rupestris. 
Azeca goodalli may also belong here, or in the next group (Adam, 1960). 

Dampness . The sites in this study are comparatively dry. One species common in 
wet woodland, Arianta arbustorum, is very rare on the South Downs (Cameron & 
Palles-Clark, 1971). Another, Vitrea crystallina, is usually replaced by V. contracta 
in drier sites (Kuiper, 1964), and is here restricted to the more acid sites. Columella 
edentula, Carychium minimum, Zonitoides nitidus, Agriolimax laevis, Succinea putris 
and Monacha granúlala, all absent from my sites, occur in many of the others, especi- 
ally in the wetter sites. All are common in wet places, and many are restricted to 
them (Boycott, 1934; Watson & Verdcourt, 1953). 

Openness . Pupilla muscorum, Vallonia excéntrica and Helicella caperata, species 
usually found in open situations, occur in a few sites elsewhere. Descriptions of the 
sites do not indicate whether clearings are present. 

Extreme acidity . Zonitoides excavatus, the only calcifuge snail in Britain (Boycott, 
1934) is found in some of the most acid woods elsewhere. 

Comparisons with other European woodland faunas 

The study area lies in the broad climatic zone of rich mixed deciduous woodlands. 
Direct comparisons with continental faunas from the same zone is difficult, because 
of variations in the geographical distribution of species within that zone, and because 
the British fauna is impoverished as a result of isolation following the loss of the land 
connection (Beirne, 1952). In many cases the same genera are represented by different 
species, but one cannot yet assume that they are ecological replacements. 

In the Netherlands, the richest woods evidently support a fauna very similar to 
those of Group C, especially if woods in the exceptionally rich Limburg region are 
included (Bruijns, Altena & Butot, 1959). As with the British woods, the list is much 
longer than that obtained here; detailed inspection of lists for each site would be neces- 
sary to see if the same factors operate. Some of the poorer woodland associations 
resemble those from Group A sites. 

There are also similarities with several types of German beechwood. The Melico- 
Fagetum and Carici-Fagetum of Ant (1969) show strong resemblances to South Downs 
beechwoods (Carychium minimum in this paper is an aggregate, so C. tridentatum is 
possibly present (Ant, pers. comm.)), with many species of high constancy in common. 
In central Germany, the Staudenbuchenwalder of Körnig (1966), and in particular the 
Hangbuchenwalder which form a sub-division of the former, contain mollusc faunas 
very similar to those reported here (Table 7). They are usually on slopes and have 
highly calcareous soils. Unlike the beechwoods studied by Ant (1969), they are appre- 
ciably richer in species than those from the South Downs. 

The mountain forests of Geneva (Favre, 1927) also show similarities to those of the 



CAMERON 367 

TABLE 6. Numbers of species of given levels of frequency occurring in each faunal group. 





GROUPS 


Frequency 


A 


В 


С 


100-75 


5 


10 


13 


74-50 


3 


5 


10 


49-25 


8 


4 


1 


25-1 


7 


4 


6 


Total 


23 


23 


31 


Absent 


10 


10 


2 



TABLE 7. A comparison of the most frequent (75%+) species in the Staudenbuchenwalder of 
Körnig (1966) and Group С sites in this study. + = frequency 75% or more, 
50+ = frequency between 50 and 75%, rare = frequency less than 25%, - = absent. 
Acicula polita and Helix aspersa are treated as potential ecological equivalents 
of A. fusca and H. pomatia. 



Ena montana 
Ena obscura 
Marpessa laminata 
Clausula bidentata 
Discus rotundatus 
Retinella nitidula 
Retinella pura 
Oxychilus cellarius 
Vitrea contracta 
Perforatella incarnata 

Hygromia hispida 
Helicodonta obvoluta 
Helix pomatia 
Acicula fusca 
Clausilia rolphii 
Oxychilus alliarius 
Carychium tridentatum 
Pomatias elegans 



S taudenbuchenwa 1 der 

+ 

+ 
+ 
+ 
+ 

+ 
+ 

+ 
+ 
+ 

+ 
+ 
+ 
- (A. polita rare) 

rare 
50+ 



Group С 



+ 

+ 

50+ 

+ 
+ 
+ 
+ 
+ 

- (absent in 

Britain) 

50+ 
50+ 

- (Я. aspersa +) 

+ 
+ 
+ 
+ 
+ 



368 PROC. FOURTH EUROP. MALAC. CONGR. 

South Downs; Retinella nitidula and Marpessa laminata are the most frequent species 
in these woods, and Discus rotundatus is obviously common (it is omitted from the list 
of woodland molluscs (Favre, p 322), but it is clear from the following text that it 
occurs frequently in woods). This list evidently represents a fairly diverse range of 
woodland types. The maximum number of species found in any one site was 31, 
surprisingly lower than figures for several British sites (Boycott, 1934; Stratton, 
1956). 

Deciduous and mixed woods, especially the more eutrophic ones, in southern Sweden, 
also have faunas containing many species (or more northerly representatives of the 
same genus, e.g., Discus ruderatus) found in South Downs faunas (Lundgren, 1954; 
Waiden, 1955; Wareborn, 1969), but the dominant species are usually smaller than 
those of England (Retinella radiatula (=Nesovitrea hammonis, Waiden 1966), Euconulus 
fulvus, P. pygmaeum), and genera such as Columella and Vertigo are well represented. 
Many of these woods must be much less disturbed, or present more niches (e.g., 
rocks, screes and clearings) than the Group A sites of this study, for many sites with 
acid soils have much richer faunas. Rather similar faunas, poorer in Helicids, come 
from central Finland (Valovirta, 1968). 

This study demonstrates that certain narrowly defined habitats in Britain do have 
characteristic faunas, which can be compared with similar ones in such a way that 
reasonable explanations can be offered for the differences. Such studies are lacking 
in Britain, yet they form a useful basis for more quantitative work on the role of 
molluscs in the woodland ecosystem (e.g., Mason, 1970). They permit the conclusions 
of such work, which is laborious to carry out in more than a few sites at once, to be 
extended with confidence to a wider area. 

SUMMARY 

1) A survey of the molluscan faunas of 44 deciduous woodland sites in Southern 
England has been carried out. 

2) Analysis of faunal affinities using the Simple Matching Index indicate the existence 
of 3 types of fauna: type A, sparse faunas associated with low soil pH and some dis- 
turbance; type B, intermediate and type C, rich faunas associated with high soil pH 
and minimal disturbance. 

3) The high levels of affinity between faunas in Group С and the high proportion of 
frequently occurring species (occurring in 50% or more of the sites examined) 
reflect the similarity of habitat between sites and the minimal effect of disturbance 
on faunas. 

4) The absence of various species found in other British woodlands is tentatively 
explained. 

5) The faunas are compared with those from various European woodlands, some of 
which are extremely similar. 

ACKNOWLEDGEMENTS 

Thanks are due to Dr. L. M. Cookfor computing the S.M.I.'s for me and for discus- 
sion of indices of affinity; to Mr. F. Haynes and Dr. D. I. Morgan-Huws for botanical 
information and ideas and to Dr. M. P. Kerney, who kindly read a draft of this paper. 
I should also like to thank Miss J. Switzer for facilities provided at Portsmouth Poly- 
technic. 



CAMERON 369 

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370 PROC. FOURTH EUROP. MALAC. CONGR. 

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MALACOLOGIA, 1973, 14: 371-376 

PROC. FOURTH EUROP. MALAC. CONGR. 

PRELIMINARY REPORT ON THE MOLLUSCA OF THE BENTHIC 
COMMUNITIES OFF TEMA, GHANA 

J. Edmunds and M. Edmunds 

Department of Zoology, University of Ghana, Legon, Ghana 

ABSTRACT 

Preliminary results from a survey of the bottom communities off Tema, 
Ghana, are discussed. Most of the bottom is of soft deposits, but there is a 
reef at 10 m and a second, more fragmentary, reef at 20 m. The dominant 
molluscs on the 10 m reef are herbivores and species which browse on sedentary 
animals such as sponges and polyzoa, but there are rather few species of active 
carnivores. The 20 m reef has a very similar fauna to the 10 m reef but with 
rather fewer algae and associated herbivores. 

Of the soft deposit communities 2 of the most interesting are composed of 
sandy silt overlaid with colonial foraminiferans, Julienella and Schizammina. 
These have very rich faunas of molluscs with abundant ciliary feeders {Turritella 
and bivalves) in the silt. There is an unusually rich variety of carnivores in 
these communities including many species of Toxoglossa. The reason why there 
are so many carnivores in this otherwise very uniform habitat whilst there are 
so few in the much more diverse reef is not known. Nudibranchs, however, are 
much more abundant on the reef than in the foraminiferan communities , since 
they browse on sponges , polyzoa and hydroids which can only grow on the reef. 

INTRODUCTION 

The offshore fauna of Ghana has been studied by Buchanan (19 54, 1958), Buchanan & 
Anderson (1955) and Bassindale (1961), all of whom concentrated on the fauna of the 
soft deposits off Accra. At present, Mr. W. Pople of the Zoology Department and Dr. 
D. John of the Botany Department at the University of Ghana are surveying a limited 
area off Tema (35 km east of Accra). The survey is being carried out in considerable 
detail by diving in the shallower regions and by dredging in deeper water. The aim of 
the study is to work out the patterns of distribution of the fauna and flora, and to 
investigate the interactions between the various species. This report covers the more 
common species of mollusc collected during the survey. They were identified from 
the publications of Nicklès(1950, 1955), Knudsen (1952, 1956), Eales (1957), Edmunds 
(1968) and Tebble (1966). We are grateful to Dr. J. Knudsen for help with identifying 
the more difficult shelled molluscs. The work is still in the preliminary stages and 
has been hampered in 1970 and 1971 by the boat having been rammed and sunk in 
Tema harbour. Collections since then have been less regular. 

The coast of Ghana east of Cape Three Points runs west-south-west to east-north- 
east with fault planes both parallel to the coast and due west-east. Tides are small 
(with a maximum difference at Spring tide of 1.5 m), but waves are high and there are 
considerable underwater currents eastwards, and a long shore drift results in changes 
in the distribution of the sand. From Tema eastwards the coast is rocky with patches 
of sand especially at the outlets of lagoons. The rock forms a platform from low tide 
level to about 10 m depth, then the bottom shelves more steeply. From East Tema 
Rocks a reef, Vernon Bank, runs eastwards into Kpone Bay. It is at a depth of about 

(371) 



372 PROC. FOURTH EUROP. MALAC. CONGR. 

10 m, and, except at its western end where it joins the shore, there is a deeper area, 
up to 16 m, between it and the 10 m shore platform (Fig. 1). From observation under- 
water, it appears that this reef is the remains of an old shoreline, composed of rock 
which probably lies along an east-west fault plane. It would have been flooded, together 
with the lagoon it enclosed, when the sea level rose. The western end of this reef 
shelves downwards on its seaward side, but further east it forms a prominent cliff. 
Beyond the reef the bottom slopes gently toa depth of 20 m where there are fragmentary 
remains of another reef which is composed largely of Dendropoma and is possibly an 
old shoreline. Beyond this the sea bottom slopes gradually to 40 m depth, then drops 
away more suddenly to 100 m which is the edge of the continental shelf. There is 
some evidence of another reef at about 30 m depth, as gorgonians and sponges have 
been dredged from here, but no more is known about it. 

The areas studied are: 1) the 10 m Kpone reef (Vernon Bank), which is studied 
mainly by SCUBA diving; 2) the deeper 20 m reef, which is studied by diving and 
dredging; 3) the soft deposits between the 2 reefs and beyond the 20 m reef to a depth 
of about 40-50 m. These areas can only conveniently be studied by dredging. The 
communities living in these soft deposits will be discussed only briefly in this paper. 

The 10 m reef (Kpone reef) 

The most common species of mollusc on the 10 m Kpone reef are herbivores and 
browsing carnivores, as one would expect in an area where there are many sea weeds, 
sponges, gorgonians, polyzoa and small tunicates (but rather few corals). Herbivores 
found are listed in Table 1. Alaba culliereti feeds, and is usually found, on Sargassum 
which characteristically grows in sandy areas of the reef, in contrast to Fissurella 
nubecula which scrapes hard surfaces and occurs only on the rocky areas of the reef. 
Aplysia winneba Eales also occurs on the reef. Individuals of this species from 2 to 6 
mm long have been collected feeding on Laurencia majuscula (Harvey) and one was 
subsequently reared until 30 mm long when identification was possible. The food 
preferences of the other herbivores are not known. 

Ciliary feeders on the reef are shown in Table 2. Except for the gastropod Crepidula 
porcellana, all are fixed bivalves. Ostrea spp. are rare but occur in groups of several 
individuals. Pteria sp. lives attached to the gorgonian Lophogorgia. Hole-living 
species such as Notirus irus and Saxicava árctica are probably more common than 
they appear from the samples, and a large species of Lithophaga may occur since it 
has been found on the 20 m reef. 

Browsers of sessile animals are shown in Table 3. From observations on species 
found elsewhere, Triphora sp. probably eats sponges (Fretter, 1951), and Erato 
prayensis tunicates (Fretter & Graham, 1962). The food of Mathilda is not known, and 
further work needs to be done on these species. Rostanga sp. and Chromodoris graci- 
lis are probably sponge feeders and may be found almost anywhere on the reef where 
sponges occur. The food of the common reef and intertidal Doriopsilla albolineata is 
not known. Several dorids feed on polyzoa, for example Onchidoris sp. eats Stylopoma 
duboisi, and Corambe sp. eats Membranipora. Trinchesia sp. and Doto sp. are 
hydroid browsers -Doto being particularly common on hydroids growing on Sargassum. 

There is a notable absence of carnivores on the reef, especially when compared with 
the fauna of the deeper water off Tema. Table 4 lists the commonest carnivores, but 
the food preferences of most are not known. At low tide Cantharus viverratus has been 
found eating a moribund sea urchin. In the laboratory a large Cassis spinosa rasped 
away at the starfish Oreaster clavatus Müller & Troschel; and Tritonalia fusiformis 
is suspected of having bored holes in Alaba culliereti. In Hawaii, Bursa eats poly- 
chaetes (Houbrick & Fretter, 1969), and species of Chrysallida are known to be ex- 
ternal parasites of bivalves (Fretter & Graham, 1962). The taxonomy of the several 



EDMUNDS and EDMUNDS 



373 




40m 



IOO m 



FIG. 1. Map of the Tema area, Ghana, showing the positions of the 10 and 20 m reefs. 



species of Nassa has not been worked out, but they are probably scavengers. 

The sandy areas of the reef are devoid of molluscs - the only ones recorded are 
Turritella ungulina (Linnaeus) and Terebra gray i E. A. Smith, but the area is not 
regularly sampled by divers. Aplysia dactylomela Rang and A. fasciata Poiret have 
both been found buried in the sandy crevices of the reef with only the mantle and its 
water currents visible. Presumably they are protected from predators, but this 



374 



PROC. FOURTH EUROP. MALAC. CONGR. 
TABLE 1. Herbivores of the 10 m reef. 



Common on the reef, rare elsewhere 



Occasional on the reef, occasional or rare elsewhere 



Solariella canaliculata E.A.Smith 
Fissurella nubecula Linnaeus 
Alaba culliereti Dautzenberg 



Rissoina sp. 
Calliostoma (2 spp. ) 
Columbella rustica (Linnaeus) 



TABLE 2. Ciliary feeders of the 10 m reef. 



Common on the reef, rare elsewhere 


Occasional on the reef, occasional or rare elsewhere 


Beguina senegalensis (Reeve) 


Area noe Linnaeus 


Spondylus senegalensis Schreibers 


Pteria spp. 




Crepidula porcellana Lamarck 




Notirus irus (Linnaeus) 




Saxicava árctica Linnaeus 




Ostrea spp. 



TABLE 3. Browsers of the 10 m reef. 



Common on the reef, rare elsewhere 


Common or occasional both on the reef and elsewhere 


Triphora sp. 

Mathilda canariensis Dautzenberg 

Philine sp. 


Erato pray ens is Rochebrune 


Occasional on reef, rare elsewhere: 


Doriopsilla albolineata Edmunds 
Chromodoris gracilis (Rapp) 
Onchidoris sp. 
Doto sp. 


Okenia impexa Marcus 

Rostanga sp. (probably R. rufescens Iredale and 

O'Donoghue) 
Trinchesia sp. (probably T. albopunctata Schmekel) 
Janolus sp. 
Coram.be sp. 



TABLE 4. Carnivores of the 10 m reef. 



Common both on the reef and elsewhere Rare on the reef 



Tritonalia fusiformis (Gmelin) 
Nassa spp. 



Occasional on the reef, rare elsewhere: 



Marginella sp. 
Cantharus sp. 
Bursa pustulosa Reeve 
Drupa nodosa C. B. Adams 
Chrysallida sp. 



Thais haemastoma (Linnaeus) 

Conus ambiguus Reeve 

Tritonalia decussata (Gmelin) 

Murex gravidus Hinds 

Cassis spinosa Gronovius 

Cantharus viverratus (Kiener) 

Fusus sp. (probably F. boettgeri von Maltzan) 



EDMUNDS and EDMUNDS 375 

behaviour does not appear to have been recorded before. 

The fauna of this reef, especially the carnivores, shows affinities to that of the shore 
and shallow sublittoral. Thais haemastoma,Cantharus viverratus. Tritonalia decussata 
and Conus ambiguus all occur commonly on the shore as well as on the reef. The 
herbivores Fissurella nubecula and the rarer Cerithium atratum Born as well as the 
bivalve Pinna radis (Linnaeus) also occur both on the reef and intertidally. Other 
reef species which can be found in the shallow sublittoral include Beguina senegal- 
ensis, Triphora sp., Mathilda canariensis, Alaba culliereti, Area noë and Doriopsilla 
albolineata. This is hardly surprising since the reef can be considered as a sub- 
merged rocky promontory of the shore. However, being at 10 m depth, some species 
which are common in deeper water are also found on the reef. Thus Tritonalia 
fusiformis and some species of Nassa are common on the reef as well as deeper, and 
Erato prayensis, Rissoina sp, one species of Calliostoma and Crepidula porcellana 
also occur in both areas. A few other deep water species are found on the reef rarely. 

The 20 m reef 

The fauna of the 20 m reef is not as well known as that of the 10 m reef, but it 
appears to be very similar except for having fewer algae and associated herbivores, 
as one would expect in view of the lower light intensity there. A few species, however, 
occur here which are absent from the 10 m reef, e.g., Cardium kobelti von Maltzan, 
Gari fervensis (Gmelin) and Drillia pyramidata (Kiener). 

The soft deposits 

The large area of sea bottom that is not reef has a variety of communities based 
on sand, mud or shell gravel, but the only ones mentioned here are the Julienella 
foetida Schlumberger and Schizammina spp. foraminiferan communities. Here the 
greyish mud is overlaid with pieces of siliceous material formed by the colonial 
foraminiferans, and the fauna here is far richer than in apparently similar deposits 
but without foraminiferans. Presumably the foraminiferans provide an additional 
solid substrate which is important for many of the species. The dominant ciliary 
feeder of the community is Turritella annulata Kiener, with the bivalves Cardium 
kobelti, Pitarla tumens (Gmelin) and Cultellus tennuis Gray also common in the mud, 
and Calyptraea chinensis (L.) on the surface. Scavengers (Phos grate loupianus (Petit) 
and Nassa spp.) are very numerous, and there is an incredible number of predatory 
gastropods such as Murex spp., Oliva flammulata Lamarck, Philine aperta L., and 
the toxiglossans Turris undatiruga (Bivona), Asthenotoma spiralis (E. A. Smith), 
Drillia spp., Clavatula spp., Terebra spp. and Conus spp. There is also a great 
variety of hermit crabs, the majority living in shells of Turritella that have been bored 
by one of the carnivorous gastropods. The richness of the molluscan fauna in this 
apparently uniform habitat contrasts strikingly with the relative paucity of the shelled 
molluscan fauna in the more varied habitat of the reef. The food of the large number 
of toxiglossans is not immediately obvious, and further work in this area would be very 
interesting. 

REFERENCES 

BASSINDALE, R., 1961, On the marine fauna of Ghana. Proc. zool. Soc. Lond., 137: 

481-510. 
BUCHANAN, J. В., 1954, Marine molluscs of the Gold Coast West Africa. J. W. Afr. 

Sei. Assoc, 1: 30-45. 
BUCHANAN, J. В., 1958, The bottom fauna communities across the continental shelf 

off Accra, Ghana. Proc. zool. Soc. Lond., 130: 1-56. 



376 PROC. FOURTH EUROP. MALAC. CONGR. 

BUCHANAN, J. B. & ANDERSON, M. M., 1955, Additional records to the marine 

molluscan fauna of the Gold Coast. J. W. Afr. Sei. Assoc, 1: 57-6L 
EALES, N. В., 1957, Aplysiids from West Africa, with description of a new species 

Aplysia winneoa. Proc. malacol. Soc. Lond., 32: 179-183. 
EDMUNDS, M., 1968, Opisthobranchiate Mollusca from Ghana. Proc. malacol. Soc. 

Lond., 38: 83-100. 
FRETTER, V., 1951, Observations on the life history and functional morphology of 

Cerithiopsis tubercularis , (Montagu) and Triphora perversa (L.). J. mar. biol. 

Assoc. U.K., 29: 567-586. 
FRETTER, V. & GRAHAM, A., 1962, British Prosobranch Molluscs. Ray Society, 

Lond., 755 p. 
HOUBRICK, J. R. & FRETTER, V., 1969, Some aspects of the functional morphology 

and biology of Cymatium and Bursa. Proc. malacol. Soc. Lond., 38: 415-429. 
KNUDSEN, J., 1952, Marine prosobranchs of tropical West Africa collected by the 

"Atlantide" expedition 1945-46. Part I. Vidensk. Medd. Dansk naturhist. Foren., 

114: 129-185. 
KNUDSEN, J., 1956, Marine prosobranchs of tropical West Africa (Stenoglossa). 

Atlantide Rep., 4: 7-110. 
NICKLÈS, M., 1950, Mollusques testacés marins de la côte occidentale d'Afrique. 

Manuel Ouest -Africains. Lechevalier, Paris, 269 p. 
NICKLÈS, M., 1955, Scaphopodes et lamellibranches récoltés dans l'Ouest Africain. 

Atlantide Rep., 3: 93-238. 
TEBBLE, N., 1966, British bivalve seashells. British Museum (Natur. Hist.), Lond., 

212 p. 



MALACOLOGIA, 1973, 14: 377-383 

PROC. FOURTH EUROP. MALAC. CONGR. 

RECORDINGS OF THE HEART RATE AND ACTIVITY OF MOLLUSCS 
IN THEIR NATURAL HABITAT 

E. R. Trueman, J. G. Blatchford, H. D. Jones and G. A. Lowe 

Department of Zoology, University of Manchester, M13 9PL, U.K. 

ABSTRACT 

A method is described of continuously recording and analysing the heart rate 
and activity of molluscs in their natural habitat. The effect of change of tempe- 
rature and valve closure on the heart rate of Isognomon illustrate the techniques. 
The possibility of developing these methods to employ sessile molluscs as en- 
vironmental sensors is discussed. 

INTRODUCTION 

Much past work on the heart rate, e.g., Welsh, 1961; Pecsi, 1968, and activity, e.g., 
Salánki, 1966, of Mollusca has been carried out in the laboratory, recordings commonly 
being made on kymographs. Knowledge of the physiological ecology of littoral molluscs 
is derived from observations of their distribution and also from experiments carried 
out largely in the laboratory (Newell, 1964). However, the development of electronic 
recording techniques, e.g., Trueman, 1967; Salánki & Vero, 1969, allows experiments 
to be carried out in the natural environment with minimal disturbance to normal 
activity. Control experiments over long periods may be conveniently carried out in 
the laboratory using the same recording technique. 

This paper consists of a description of the recording technique used, illustrated 
by extracts from recordings of Chiton, Patella, Isognomon and Anodonta, which show 
the effect of temperature change or valve closure on the heart rate. A technique of 
analysing the large amount of data that may be obtained is described and its use is 
discussed. 

METHODS 

Véró & Salánki (1969) have described a method of continuously recording the move- 
ment of the valves of Anodonta while in the natural environment. This involved the 
attachment of coils of fine wire to the valves and allowed Salánki & véró (1969) to 
study the diurnal rhythms of activity of this mussel. It is, however, convenient to 
record both heart rate and valve movements simultaneously by use of an impedance 
pneumograph connected to a multichannel pen recorder both commercially available 
from Narco Biosystems Inc. The impedance pneumograph, which was originally 
designed to monitor chest volume in mammals, has proved to be an extremely versa- 
tile transducer. A small oscillating current (25 Kc/s, 2/xA) is passed between a pair 
of fine platinum or silver wire electrodes and any changes in impedance that occurs 
between them is converted into a voltage signal. This is amplified to drive a pen in 
the recorder (Fig. la). The electrodes may be attached 1 to each valve of a bivalve 
to record shell movements or inserted into the pericardial cavity through fine holes 
drilled through the valves to monitor heart rate additionally. The electrodes are then 
sealed in place by wax (Fig. 2). Changes in impedance are recorded in respect of 
heart beat, valve movements and possibly pedal and rectal movements. Mussels 

(377) 



378 PROC. FOURTH EUROP. MALAC. CONGR. 

Animal Transducer Pen Recorder Auxiliary equipment 







Drive 


Imp 






Amplifier 









Pen 



Imp 



Drive 



Amplifier 



Pen 



Tape recorder 



Imp 



Drive 



Amplifier 



Pen 



Tape recorder 



Rate meter 



a. 

lJ 



I mp 



Drive 



Amplifier 



Pen 



Rate meter 



FIG. 1. Diagram showing ditlerent recording techniques. The animal (left) is connected to an 
impedance pneumograph transducer (Imp). Recording equipment comprises transducer drive 
(Drive), signal amplifier (Amplifier) and pen output (Pen). Broken line after tape recorder indi- 
cates replay of tape at any time after recording. 

with electrodes inserted in this manner have been used for recordings for at least 
several weeks in the field and several months in the laboratory. Recordings of 
pressure in the pericardium and electrocardiographs confirmed that the heart beat 
was being satisfactorily recorded. This general technique and the same transducer 
may be used to record activity in any part of small sessile invertebrates, e.g., 
barnacles (Blatchford, 1970), dependent on the position of implantation of the electrodes. 
The electrodes were joined to the impedance pneumograph by fine twin core flexible 
screened cable (Fig. la). Lengths of up to 100 m are used so that the mollusc can be 
in the sea some distance away from the recording instrument. The number of ani- 
mals sampled continuously was limited to the number of pneumographs and recording 



TRUEMAN, BLATCHFORD, JONES and LOWE 379 




FIG. 2. Diagram of transverse section of the pericardium (pc) of a bivalve showing location of 
electrodes (e) passing through the shell (s) on either side of the ventricle (v) and embedded in 
wax (stipple). 

channels available on the pen recorder. 

Using this technique recordings of heart beat suchas shown in Fig. 3 were obtained. 
Analysis of these traces is easy over relatively short periods and, although examination 
of continual recordings of long duration is feasible, it is rather exhausting. One 
modification involves the replacement of the usual pen output by a long playing tape 
recorder (Phillips ANA - LOG 7) (Fig. lb) which can store up to 7 channels of 
information on tape and runs for about 12 hours unattended. Such tapes can be ana- 
lysed at a later date either by means of sample periods being transferred to paper 
or by means of a Nielson Instantaneous Ratemeter (Devices Instruments Ltd) (Fig. lc). 
It is possible to analyse tapes very rapidly by speeding up the tape recorder provided 
a steady record has been obtained free of electrical interference. When the ratemeter 
output is fed into the pen recorder a time/rate curve is produced (Fig. 4). Finally 
this system may be modified to record the heart rate instantaneously by elimination 
of the tape recorder (Fig. Id). 

EXPERIMENTAL RESULTS 

The regular rhythm of the heart beat is typically recorded from a bivalve as shown 
for Isognomon (Fig. 3c) either during continual immersion in the sea or in the labor- 
atory. These recordings may be readily obtained from all species of bivalves. Similar 
recordings may be taken from polyplacophorans and gastropods (Figs. 3a and b) with 
the electrodes inserted through the shell into the pericardium about 1 cm apart. This 
technique also gave perfectly satisfactory results with bivalves, although electrodes 
are generally placed 1 through each valve. No problems were encountered in using 
this technique on the large West Indian Chiton tuberculatus L. except that it was dif- 
ficult to drill through the thick and tough shell. Recordings were also easily obtained 
from Patella vulgata L. (Jones, 1968), but gastropods with coiled shells are more 
difficult. It is possible to produce traces from the heart of Helix, but movement of 
the viscera within the shell when the foot is protracted makes the technique very 
difficult in this class. 

The amplitude of heart beat recorded remains at approximately the same amplitude 
for successive beats due to the impedance change between a pair of electrodes being 



380 



PROC. FOURTH EUROP. MALAC. CONGR. 





FIG. 3. Examples of recordings of the heart beat of a, Chiton tuberculatus;h, Patella vul gata; 
с, Isognomon alatus . The latter shows the immediate effect of change of temperature on heart 
rate. Time traces in minutes. 



constant for similar contractions. It is not possible to calibrate the traces in respect 
of amplitude of deflection, but it is reasonable to assume that an increased amplitude 
of deflection represents a larger contraction and a greater heart output. This com- 
monly occurs after a littoral bivalve, e.g., Cardium, has been reimmersed by the 
tide (Trueman, 1967). However, with a constant amplitude of contraction the base line 
of the recordings may fluctuate. A downward deflection of the trace indicates a 
reduction of impedance between the electrodes and conversely an increase for an 
upward swing. Thus adduction of the valves of Bivalvia gives rise to a negative spike 
(Fig. 5 A) whereas pedal retraction may produce a positive deflection in all classes. 
The latter is probably shown centrally in the recording from Patella (Fig. 3b). 

During continual immersion many bivalves exhibit little change in heart rate in 
respect of tidal or light changes (Trueman & Lowe, 1972) but respond rapidly to 
changes in water temperature. This is shown for Isognomon alatus (Gmelin) in re- 
spect of a rapid drop in temperature (Fig. 3c). Fig. 4 illustrates a slow rise of 
temperature for Anodonta, recorded by thermistor probe, the recording being made 
on tape (Fig. lc) and played back onto paper at a higher speed so as to display events 
taking place over 160 min. in 5 min. The heart beat at the beginning and near the end 
of the recording (Fig. 4 A and B) was recorded as a check on the ratemeter values. 
Anodonta cygnea proved particularly suitable for use with the ratemeter since it gave 



TRUEMAN, BLATCHFORD, JONES and LOWE 
valves closed 



381 




\А^НАулу*^Ч % *УТ^ 



valves closed 



^^V^yW^^ 




i 1 1 1 1 1 r 

FIG. 4. Recordings of heart rate (beats/min. ) using ratemeter and temperature (°C) if ubgakebt 
water current showing the effect of raising the temperature over a period of 160 min. Actual 
heart beat at beginning and end of period shown in A and В respectively. 




1 TT 



FIG. 5. Field recording of heart beat of Isognomon alatus during a spontaneous period of valve 
closure with consequent suppression of the heart. The lower trace follows the upper with an 
interval of 5 min. Time trace in minutes. A, adduction of valves. 



a heart record with a steady base line and near constant amplitude. Traces showing 
major fluctuations as in Fig. 5 are as yet unsuited for this technique for they require 
continual adjustment of the ratemeter. 

Long term recordings of bivalves constantly immersed may commonly show little 
short term fluctuation of activity butin some, e.g., Isognomon alatus, the valves may 



382 PROC. FOURTH EUROP. MALAC. CONGR. 

remain closed for a short time. This occurs after several adductions, and the 
heart almost completely ceases to beat. It may be noted that the heart commences 
to beat more strongly before the valves reopen, possibly to ensure circulation of the 
blood through the gills to meet the new inhalent water current (Trueman & Lowe, 1971). 
Analysis of these valve movements over 7 day periods shows little obvious correlation 
to environmental factors and more exhaustive recordings are required to investigate 
this feature further. 

DISCUSSION 

The techniques described afford a means of long term monitoring of the activity 
of sessile invertebrates in their natural habit. Some results of preliminary investi- 
gations are already available (Helm & Trueman, 1967; Jones, 1968; Trueman & Lowe, 
1971) and it is hoped to considerably extend these in the near future by use of the 
ratemeter technique. Before such recordings can be understood in terms of the 
animal's response to environmental change, extensive laboratory recordings are 
required under constant conditions so that the effect of isolated factors such as 
temperature, light, salinity or food may be studied. The results of some such investi- 
gations are already in press (Lowe & Trueman, 1972; Coleman & Trueman, 1971). 

One of the snags of this method is that a continuous record is obtained of a single 
animal or, even if several channels of the recording equipment are used, only of a 
small number of animals. Preliminary experiments indicate that it may be possible 
to monitor up to 12 animals on a single channel by automatically switching from one 
to another. This would enable a statistically significant section of a population to be 
sampled over long periods and the seasonal effects of breeding and fluctuating food 
supplies to be studied. 

Preliminary experiments with A nodonta have indicated that the normal heart rate and 
activity is suppressed when water is chlorinated. Further studies are clearly required 
on the effects of environmental changes and of pollution. If the heart rate and activity 
of bivalves are sensitive to pollutants then it is tempting to suggest that these animals 
could be used as living environmental sensors. But this will require the development 
of the techniques described here and a much greater understanding of the animals' 
reactions to environmental changes. 

REFERENCES 

BLATCHFORD, J. G., 1970, Possible circulatory mechanism in an operculate cirripede. 

Comp. Biochem. Physiol., 34: 911-915. 
COLEMAN, N. & TRUEMAN, E. R., 1971, The effect of aerial exposure on the activity 

of the mussels Mytilus edulis L. and Modiolus modiolus (L.). J. exp. mar. Biol. 

Ecol., 7: 295-304. 
HELM, M. M. & TRUEMAN, E. R., 1967, The effect of exposure on the heart rate of 

the mussel Mytilus edulis L. Comp. Biochem. Physiol., 21: 171-177. 
JONES, H. D., 1968, Some aspects of heart function in Patella vulgata L. Nature, 

217: 1170-1172. 
LOWE, G. A. & TRUEMAN, E. R., 1972, The heart and water flow rates of Mya 

arenaria (Bivalvia: Mollusca) at different metabolic levels. Comp. Biochem. 

Physiol., 41 A: 487-494. 
NEWELL, G. E., 1964, Physiological aspects of the ecology of intertidal molluscs. 

In: Physiology of Mollusca. Vol. I, p 59-81. Wilbur, K. M. & Yonge, C. M. (Eds.). 

New York, Academic Press. 
PÉCSI, T., 1968, Contributions to the innervation of the heart in the freshwater mussel 



TRUEMAN, BLATCHFORD, JONES and LOWE 383 

Anodonta cygnea L. Acta biol. Acad. Sei. hung., 19: 1-10. 

SALÂNKI, J., 1966, Daily activity rhythm of two mediterranean Lamellibranchia 
(Pectén jacobaeus & Lithophaga lithophaga) regulated by light-dark period. Annal. 
Biol. Tihany, 33: 135-142. 

SALANKI, J. & VÉRÓ, M., 1969, Diurnal rhythm of activity in fresh water mussel 
(Anodonta cygnea L.) under natural conditions. Annal. Biol. Tihany, 36: 95-107. 

TRUEMAN, E. R., 1967, Activity and heart rate of bivalve molluscs in their natural 
habitat. Nature, 214: 832-833. 

TRUEMAN, E. R. & LOWE, G. A., 1971, The effect of temperature and littoral expo- 
sure on the heart rate of a bivalve mollusc, Isognomon alatlis, in tropical condi- 
tions. Comp. Biochem. Physiol., 38A: 555-564. 

VÉRÓ, M. & SALANKI, J., 1969, Inductive attenuator for continuous registration of 
rhythmic and periodic activity of mussels in their natural environment. Med. & 
biol. Engng., 7: 235-237. 

WELSH, J. H., 1961, Neurohormones of Mollusca. Amer. Zool., 1: 267-272. 



MALACOLOGIA, 1973, 14: 385-389 

PROC. FOURTH EUROP. MALAC. CONGR. 

RECHERCHES SUR L'ECHAUFFEMENT DE CEPAEA NEMORALIS (L.) 
PAR L'ENERGIE RAYONNEE 

M. C. Garcia 

Laboratoire de Zoologie, Ecole Normale Supérieure, Paris, France 

Des observations dans la nature ont amené à penser que les températures extrêmes 
supportées par les Cepaea nemoralis dans quelques milieux aux conditions climatiques 
ou microclimatiques assez rudes pourraient être à l'origine d'une action sélective 
du milieu vis-à-vis de quelques phénotypes. C'est pour essayer de répondre en partie 
à cette hypothèse que nous avons entrepris cette étude. 

Nous avons fait, fondamentalement, deux types d'expériences: d'une part, réchauf- 
fement d'escargots placés directement au soleil, d'autre part, l'étude de la variation 
de leur température, par l'action de l'énergie rayonnêe par une ampoule Mazdasol de 
150 à 300 watts, placée dans une enceinte en bois. Nous avons considéré non seulement 
les animaux vivants mais aussi deux séries d'essais d'échauffement de coquilles 
vidées de leurs corps et constituant des échantillons statistiquement homogènes quant 
à la taille, à la hauteur et au poids, c'est-à-dire donc aussi quant à l'épaisseur de la 
coquille; il est évident que, dans ces conditions, on écarte encore tous les éléments 
concernant la variabilité du corps de l'animal, due notamment à sa masse et à sa 
pigmentation, aussi bien qu'à son comportement physiologique. Pour notre étude nous 
avons choisi deux séries de coquilles, les premières de la race des Pyrénées, grandes 
et épaisses, les autres de petite taille et de faible calcification, et nous les avons 
remplies d'un certain volume d'agar-agar à 2% (3,5 ce pour la première série; 2 ce 
pour la seconde). 

Dans les expériences d'ensoleillement direct, on utilisa à chaque fois un lot d'indi- 
vidus de taille approximativement égale, appartenant à différents phénotypes d'une 
même population. Les escargots étaient attachés à une plaque en bois par des brace- 
lets en caoutchouc, l'apex tourné vers le haut. Les expériences furent toujours 
réalisées au mois de juillet entre 11 et 16 heures et permettaient l'enregistrement de 
la température du pied au moyen de thermocouples introduits dans les coquilles 
(Fig. 1). 

Dans tous les autres cas, nous avons utilisé une enceinte en bois à dimensions 
variables selon le type d'expérience; au plafond, on plaçait une ampoule Mazdasol et 
l'on disposait à la base une plaque circulaire - plan de travail - sur laquelle avaient 
été creusées, au préalable, de petites encoches où l'on attachait les escargots (Fig. 
2 à 4). 

Dans les expériences de type I, réchauffement se fait par intermittence, c'est-à- 
dire qu'il y a un mécanisme thermostatê qui coupe le courant de l'ampoule chaque 
fois que la température de la sonde, placée à l'intérieur de l'enceinte, atteint un cer- 
tain niveau. Nous avons utilisé une enceinte de 44 x 44 x 58 cm avec une ampoule de 
150 ou 250 watts et adopté des températures allant de 39 à 42°C; l'homogénéisation 
thermique au niveau des emplacements à escargots se faisait au moyen d'un mouve- 
ment circulaire uniforme du plan de travail (2,5 tours/min.). 

Dans les expériences de type U, on disposait d'une grande enceinte (61 x 61 x 104 
cm), d'une ampoule de 300 watts et d'un élément étalon pour le contrôle thermique; 
on enregistrait la température de quelques individus placés à des endroits du plan 
de travail soumis à un même échauff ement. On a considéré des escargots à épiphragme 
épais et d'autres ne renfermant pas d' épiphragme calcifié. 

(385) 



386 



PROC. FOURTH EUROP. MALAC. CONGR. 








FIG. 1. Schema du dispositif utilise dans les experiences d'échauffement d'escargots par le 

soleil avec enregistrement de température. 

FIG. 2. Schéma du dispositif utilisé dans les expériences de type I. 

FIG. 3. Schéma du dispositif adopté dans les expériences de type II. 

FIG. 4. Plan de travail utilisé dans les expériences d'échauffement de coquilles. 



GARCIA 



387 



TABLEAU 1. Mortalité totale observée chez des escargots des Basses Pyrénées soumis à 
échauffement par l'énergie rayonnée par une ampoule Mazdasol, pendant 15 
jours après l'expérience. 





T 
Jaunes 


Roses 




00000 


12345 


00000 


12345 


Population Y 
(Sauve terre) 


36 
ÏÏÔ 


(60,0%) 


f$ (61,6%) 





(0 %) 
4 


m (53,3%) 
— > 




<— 




— > 








< 






Population D 
(St Gladie) 


16 
30 


(53,3%) 


Щ (66,6%) 


22 
30 


(73,3%) 


3$ (76,6%) 


Population E 
(Maulé on) 


4 
30 


(13,3%) 


Щ (66,6%) 


15 
30 


( 50%) 


Щ (100%) 


< — 




_* « — 


— >• 




4— 


— > 







Les expériences de type III ne durent que 12 à 18 min., pendant lesquelles la 
plaque fait seulement 2 tours; il s'agit d'un échauffement intensif sans enregistrement. 
L'enceinte est petite (44 x 44 x 58 cm), l'ampoule de 250 watts. 

Pour réchauffement des coquilles on a repris la grande enceinte (61 x 61 x 104 cm). 
Des éléments utilisés comme étalon nous ont permis de déterminer, au préalable, les 
emplacements soumis à un même échauffement et de choisir deux groupes de trois 
encoches chacun, à l'intérieur desquels les conditions d' échauffement étaient iden- 
tiques. Nous avons donc considéré ensemble les deux séries de coquilles, en sachant 
que l'une des séries subirait un échauffement plus intense. 

Les résultats obtenus (mortalité immédiate, mortalité totale 15 jours après 
l'expérience, température des individus, perte de poids) sont, au premier abord, très 
hétérogènes; on trouve en effet des populations où la mortalité se traduit par des 
chiffres presque opposés pour les différents phénotypes. Parfois, dans des populations 
très rapprochées gêographiquement, d'une même région naturelle, on en trouve une 
dont un phênotype a une réponse tout à fait inattendue, soit une mortalité en masse, 
soit, précisément, une résistance à toute épreuve. Ne pouvant pas présenter et dis- 
cuter ici tous ces résultats, nous nous bornerons à en donner un exemple, celui de 
trois populations des Basses Pyrénées distantes entre elles de moins de 30 km et à 
caractères morphologiques identiques (Tableau 1). 

Les données obtenues concernant les températures montrent que les formes rayées 
s'échauffent plus fortement que les sans bandes et que, lorsqu'on compare les 
phénotypes roses et jaunes, les premiers subissent souvent un plus grand échauffement 
(Fig. 5, 6); cependant, d'autres caractères particuliers de chaque coquille (épaisseur, 
intensité de coloration de fond, taille) jouent un rôle aussi important et sont certaine- 
ment, en partie, l'une des raisons de l'hétérogénéité observée. 

La forte épaisseur de la coquille constitue une bonne protection contre la chaleur 
et les individus déshydratés et à épiphragme bien calcifié, s'ils sont bien protégés 
contre le dessèchement, sont aussi ceux qui accusent les températures les plus 



388 



PROC. FOURTH EUROP. MALAC. CONGR. 



°C 

41_ 
40- 
39_ 
38_ 
37- 



\+' 



\IÚ- 



á 



•i,+ 



J00000 J00300 J00345 J12345 R00000 R00300 R00345 R12345 B00000 



série 1 
série 2 
série 3 



série 4 

^ série 5 



°C 

41 _ 
40_ 
39_ 
38- 
37_ 



H + 



Ж 



JOOOOO ROOOOO R00300 R00345 R12345 



séries 1 et 2 (12 individus) 

séries 3 et 4 (11 individus) 

series 1,2,3 et 4 (23 individus) 



FIG. 5. Representation graphique des températures enregistrées pendant réchauffement solaire 
direct d'escargots de la population de Asson (Hautes- Pyrénées). Le trait horizontal correspond à 
la moyenne (m± s m ). 

FIG. 6. Représentation graphique des températures enregistrées pendant réchauffement solaire 
direct d'escargots de Asson (Hautes- Pyrénées). Grouppementdes résultats de différentes series. 
Le trait horizontal correspond à la moyenne (m± s m ). 

élevées pendant réchauffement. Ils perdent, en effet, moins de poids pendant réchauf- 
fement mais les formes les plus hydratées trouvent dans la perte d'eau un moyen de 
régulation de température, si minime soit-elle, qui peut les protéger dans certaines 
limites. 



GARCIA 389 

BIBLIOGRAPHIE 

BOETTGER, С. R., 1954, Zur Frage der Verteilung bestimmter Varianten bei der 
Landschneckengattung Cepaea Hed. Biol. Zentralbl., 73: 317-333. 

CHARGELEGUE, A., 1960, Recherches sur le comportement de divers phénotypes de 
Cepaea nemoralis . Thèse de la Fac. Sei. Paris. 

CHESNE, J., 1960, Recherches sur le comportement de divers phénotypes de Cepaea 
nemoralis vis-à-vis de la température. Thèse de la Fac. Sei. Paris. 

LAMOTTE, M., 1966, Les facteurs de la diversité du polymorphisme dans les popula- 
tions naturelles de Cepaea nemoralis (L.). Lav. Soc. malacol. ital., 3: 33-73. 

RESUME 

Pour essayer de déceler l'importance de l'ensoleillement chez les différents 
phénotypes de Cepaea nemoralis L., on a réalisé plusieurs expériences d'échauffement 
d'escargots de cette espèce, soit par l'énergie solaire directe, soit par le rayonne- 
ment d'une ampoule Mazdasol de 150 à 300 watts. On s'est intéressée à plusieurs 
aspects: mortalité survenue, variation de la température du pied, perte de poids. On 
a encore considéré deux séries de coquilles, homogènes quant à la taille et au poids, 
vidées de leurs corps et remplies d'agar-agar à 2% et déterminé leur échauffement 
différentiel. 

Les résultats obtenus sont très hétérogènes mais on peut dire que, dans l'ensemble, 
les formes avec bandes s'échauffent plus fortement que les formes sans bandes, de 
même que les phénotypes roses par rapport aux jaunes. D'autres facteurs importants 
sont aussi l'épaisseur et la taille de la coquille, aussi bien que l'état hydrique de 
l'animal. 



MALACOLOGIA, 1973, 14: 391-392 

PROC. FOURTH EUROP. MALAC. CONGR. 

ASPECTS OF FEEDING AND GROWTH IN LAND SNAILS 

June E. Chatfield 

Department of Biology, Portsmouth College of Education 
Locksway Road, Portsmouth, U.K. 

Although general accounts of food materials are given in the literature, there is 
relatively little work giving precise details of eating habits of land snails. The present 
paper investigates feeding and growth in 2 species of helicid snails, one Monacha 
cantiana (Montagu) which lives in open habitats and the other, Hygromia striolata (Pfeif- 
fer) which is to be found in both open edge habitats and in woodlands. In some situ- 
ations (e.g., roadside banks) these 2 species are abundant together in the same plant 
community. 

Microscope studies of faecal strings and gut contents from populations of these 2 
snails near Reading, Berkshire, showed that they had fed on a variety of food plants 
including both green and decaying leaves; the type of food ingested varied with the 
time of year. More green food was taken during summer. 

Some experiments were set up to test the growth of young Monacha cantiana and 
Hygromia striolata on various food materials. The snails were collected from a 
nettle patch on Portsdown Hill near Portsmouth during September and November 
1970. They were kept in petri dishes and provided with food, moisture and chalk. The 
foods were green leaves of Armoracia rusticana (horseradish), lettuce, beech litter, 
oak litter and filter paper; each snail had access to only 1 type of food. The lip of 
the shell was marked with black waterproof ink and subsequent growth of new shell 
measured using a calibrated micrometer eye-piece. 

The results of the experiments (Fig. 1) showed that only specimens of Monacha 
cantiana and Hygromia striolata which had fed on green leaf material showed any 

TABLE 1. Food plants identified in the gut contents of Monacha 
cantiana and Hygromia striolata feeding in their natural 
habitat. The snails were collected from a number of 
sites in Berkshire and Surrey. 



Monacha cantiana 


Hygromia striolata 


Urtica dioica 


Urtica dioica 


Lamium album 


Lamium album 


Anthriscus sylvestris 


- 


Heracleum sphondylium 


- 


Cirsium arvense 


- 


Glechoma hederacea 


Glechoma hederacea 


- 


Mercurialis perennis 


- 


Fagus sylvatica litter 


Brachypodium pinnatum 


- 


Dactylis glomerata 


- 


Grasses undetermined 


Grasses undetermined 


Flower petals 


- 


Fungal hyphae 


Fungal hyphae 



(391) 



392 



CHATFIELD 



MONACHA 



_ 4 - 



CA N TIANA 

20 snails 



hYG ROMIA 



2 " [•£■■ 

I 



nil nil 



STRIOLA TA 
4 5 snails 



nil 



nil 



JZU 



Armoracia 
Lettuce Beech 



Oak 



Armorac ia 
Lettuce Beech 



Oak 



Paper Leciuce Beech Paper 

FIG. 1. Diagram to show the total growth at the shell lip of Monacha cantiana and Hygromia 
striolata during 3 weeks at 9-22 C. The specimens of Monacha cantiana were 6. 5-11. 5 mm 
shell diameter and Hygromia striolata were 5. 0-10. mm. 

continued growth of new shell. No growth was recorded in specimens feeding on 
beech or oak litter and negligible growth on filter paper. All the food materials were 
acceptable and readily ingested by the snails. Growth of snails kept on leaf litter was 
restored when the diet was changed to lettuce. 

It is evident from this investigation that the snails will eat most available food 
materials in their environment, but different foods ingested in the same quantity have 
different growth potential. 

RESUME 

Cet exposé décrit des recherches sur la nourriture et la croissance des deux espèces 
d'escargots helicidês, Monacha cantiana et Hygromia striolata, qui habitent les talus 
au bord des routes. 

Les jeunes escargots étaient nourris d'un seul genre de nourriture, d'humidité et 
de craie. Afin de mesurer la croissance consécutive, on marqua le peristome de la 
coquille avec de l'encre. Les deux espèces grandissaient lorsqu'elles mangeaient des 
feuilles vertes de laitue et de raifort. Cependant, nourries de feuilles mortes de hêtre 
ou de chêne, elles ne grandissaient point et nourries de papier filtre, elles grandissaient 
très peu. Néanmoins les jeunes escargots acceptaient et mangeaient toute les nourri- 
tures qu'on leur offrait. Ceux qu'on avait nourris de feuilles mortes de hêtre ou de 
chêne recommencèrent à grandir dès qu'on leur offrit de la laitue. 



MALACOLOGIA, 1973, 14: 393-395 

PROC. FOURTH EUROP. MALAC. CONGR. 

DER EINFLUSS VON TEMPERATUR UND PHOTOPERIODE AUF DEN LEBENSZYKLUS 
EINIGER SÜSSWASSERPULMONATEN 1 

Gerhard Imhof 

77. Zoolog. Institut, Universität Wien, Austria 

ABSTRACT 

The infraspecific variability in life-cycles of freshwater pulmonates raises the question about the influ- 
ence of temperature and photoperiodism on growth and reproduction. Groups of 4 species of lymnaeids 
and planorbids reared under controlled conditions showed some capacity for active growth regulation in 
relation to temperature within the range prevailing during the warm season - this capacity being developed 
during the early postembryonic growth. Above specific threshold values there is no correlation between 
temperature level and the intensity of spawning. Photoperiodism does not influence growth, but lengthening 
of daylight stimulates spawning in lymnaeids, and if combined with a rise in temperature, in planorbids, 
too. Whereas growth and reproduction continues steadily under constant conditions, distinct activity periods 
exist in the natural life-cycle which can be induced by imitating the natural course of seasonal climatic 
conditions in the laboratory. These results lead to the conclusion that the natural life-cycle is controlled 
by a sequence of climatic conditions, and that any intrinsic seasonal rhythm must be synchronized by the 
periodicity of temperature and daylight to become effective. 

ZUSAMMENFASSUNG 

Wie aus Arbeiten verschiedener Autoren der letzten 2 Jahrzehnte bekannt ist, zeigen die Lebenszyklen 
der Süsswasserpulmonaten eine starke infraspezifische Variabilität, welche sich auf die Anzahl der Gene- 
rationen pro Jahr, die Jahreszeit des stärksten Wachstums und der Reproduktion, sowie die bei Beginn 
der Eiablage erreichte Grösse erstreckt. Zur Klärung der Frage, wieweit klimatische Faktoren für die 
Steuerung der Lebenszyklen von Populationen verschiedener Standorte verantwortlich sind, wurden exper- 
imentelle Untersuchungen über den Einfluss von Temperatur und Photoperiodik auf Wachstum und Repro- 
duktion in Aquarienkulturen unter kontrollierten Bedingungen durchgeführt. 

Kohorten von Lymnaea stagnalis L., L. peregrai. ovata Drap., Planorbarius corneus (L.) und Planorbis 
planorbis (L.), die vom Ei an bei optimalem Futterangebot unter verschiedenen konstanten Temperaturen 
aufgezogen wurden, zeigten eine partielle Temperaturunabhängigkeit des Wachstums (Abb. 1). Die Reaktionen 
auf gebotene Temperaturänderungen im Verlauf des Heranwachsens legen ferner die Schlussfolgerung 
nahe, dass zumindest eine Anzahl von Süsswasserpulmonaten der gemässigten Zone innerhald des vor- 
herrschenden sommerlichen Temperaturbereiches zu aktiver Wachstumsregulation befähigt sind, welche 
jedoch erst postembryonal ausgebildet wird. Hinsichtlich der Reproduktion bestehen artspezifische Schwell- 
enwerte (zwischen 7° und 12°), unterhalb welcher keine Eiablage stattfindet. Oberhalb derselben 
wurde keine Korrelation zwischen Beginn und Intensität der Eiprodukten einerseits und der herrschenden 
Temperatur andererseits gefunden. Während die Tageslichtlänge auf das Wachstum keinen unmittelbaren 
Einfluss ausübt, zeigten Vergleiche zwischen Kulturen bei Langtag(16 Std.) und solchen bei Kurztag (8 Std.) 
bei den Lymnaeiden eine reproduktionsfördernde Wirkung des Langtags. Die Eiablage wird auch durch 
Tageslichtverlängerung stimuliert, ebenso wie durch Temperaturerhöhung, wobei jedoch erstere dominiert, 
wie kombinierte Versuche zeigten. Bei allen Arten wirkt eine Kombination von Temperaturerhöhung und 
Tageslichtverlängerung stark stimulierend. Gleichzeitig wurde eine Koppelung zwischen Reproduktion 
und Wachstum festgestellt, indem induzierte Intensivierung bzw. Abschwächung der Reproduktion eine 
gleichsinnige Reaktion des Wachstums bewirkt. 

Während unter konstanten Bedingungen das Wachstum kontinuierlich verläuft, und die Reproduktion über 
lange Zeit mit unregelmässigen Intensitätsschwankungen andauert, kann durch künstliche Imitation des 
natürlichen Jahresganges von Temperatur und Photoperiode der natürliche Lebenszyklus mit distinkten 
Aktivitätsphasen induziert werden, wie dieser für jede Art aus demographischen Studien im natürlichen 
Wohngewässer der Versuchstiere (Schilfgürtel des Neusiedlersees/Österreich) bekannt ist (Abb. 2). 
Aufgrund der experimentellen Ergebnisse lässt sich der natürliche Lebensablauf als eine Folge von Re- 
aktionen auf klimatische Bedingungsabfolgen erklären, und zwar bei der einjährigen Art L. ovata voll- 
ständig, und bei den übrigen, 2-jährigen Arten (mit je einer frühjährlichen Reproduktionsperiode in den 
beiden aufeinanderfolgenden Jahren) mit Ausnahme der sommerlichen Stagnation. Als Ursache für letztere 
kommen neben Erschöpfung nach frühjährlicher Aktivitätskonzentration v.a. ein endogener Jahresrhythmus 
in Betracht, welcher jedoch nur bei Synchronisation durch den natürlichen Jahresgang von Temperatur 
und Photoperiode wirksam werden kann. 



Die ausführliche Publikation dieser Untersuchungen wird voraussichtlich in "Oecologia" 1974 erscheinen. 



(393) 



394 



PROC. FOURTH EUROP. MALAC. CONGR. 



L. stagnalia 




nm 


P.corneus 




30 




^— — "— " /П ° 






-*" 23" 


2o 






















^____ 41 e 


•» 







« Monatí 



12 Monate 



-IS 




P. planorbis 

.- — Г" 


23° 


G * 




--^=ss 


/|/(0 


s 




^ 





mm 


L.ovata 






20 




23° 




15 




¿S"^ 17° 


. ' ' 4Г 


G— 








í 









-I2 Monate 



ABB. 1. Mittlere Wachstumsverläufe unter konstanten Bedingungen. Ordinate: lineare Gehäusegrösse; 
G = mittlere Grösse bei Beginn der Eiablage. - Bei der Versuchstemperatur 5° findet kein Wachstum statt. 



Freiland 



Wassertemp. 



mm 



30 - 



20 



10 




AMJJA30NDJFMAMJJAS0NDJFMAMJJAS0NDJ 




ABB. 2. Vergleich der Wachstumsverläufe und Reproduktionsperioden (Punktierung) einer Generation von 
Planorbarius corneus im Freiland und im Laboratorium (K = Kurztag; L = Langtag). 



MCDONALD 395 



LITERATUR 



BERRIE, A. D., 1965, On the life-cycle of Lymnaea stagnalis in the west of Scotland. Proc. malacol. Soc. 

Lond., 36: 283-295. 
CLAMPITT, P. T., 1970, Comparative ecology of the snails Physa gyrina and Physa integra. Malacologia, 

10: 113-151. 
DeWITT, R. M., 1955, The ecology and life history of the pond snail Physa gyrina. Ecology, 36: 40-44. 
DUNCAN, С J., 1959, The life cycle and ecology of the freshwater snail Physa fontinalis . J. anim. Ecol., 

28: 97-117. 
HUNTER, W. R., 1961, Annual variations in growth and density in natural populations of freshwater snails 

in the west of Scotland. Proc. zool. Soc. Lond., 136: 219-253. 
HUNTER, W. R., 1961, Life cycles of four freshwater snails in limited populations in Loch Lomond, with a 

discussion of infraspecific variation. Proc. zool. Soc. Lond., 137: 135-171. 



MALACOLOGIA, 1973, 14: 395-396 

PROC. FOURTH EUROP. MALAC. CONGR. 

ACTIVITY PATTERNS OF LYMNAEA STAGNALIS (L.) IN RELATION TO 
TEMPERATURE CONDITIONS: A PRELIMINARY STUDY 1 

S. C. McDonald 

Museum of Zoology, University of Michigan, Ann Arbor, Michigan, U.S. A. 

ABSTRACT 

Life is a low-temperature phenomenon. Other things being equal, below-normal temperatures are less 
damaging to the biochemical integrity of an organism than above-normal temperatures. For this reason, 
the rapidly expanding use of rivers and lakes for domestic and industrial cooling purposes poses a threat 
to aquatic life and necessitates the study of the effect of elevated temperatures upon aquatic organisms. 

Temperature is an environmentally relevant aspect of an organism's life. It is a major parameter of 
virtually all biological activities, affecting chemical reaction rates which in turn affect an organism's 
physiology and ultimately its behaviour. Yet, the thermal problem facing aquatic organisms is not par- 
ticularly the avoidance of biochemical damage from temperature extremes but rather the maintenance of 
effective organic integrity by regulating the balance among the rates of various chemical activities. This 
regulation in poikilotherms, such as the cold-water snail Lymnaea stagnalis, must manifest itself in 
behavioural responses or in changes in activity rates since poikilotherms passively follow the environmental 
temperature and expend virtually no energy on thermoregulation. 

In general, research on the effects of different temperatures on mollusks has dealt with geographic 
distribution, relative abundance and physiological responses, particularly growth and reproduction. A 
neglected area of study is that of behavioural responses (Welch & Wojtalik, 1968); especially lacking are 
quantitative studies of behavioural responses. The aim of this experiment is to provide such a quantitative 
study. 

The long-range objective of this study is to ascertain, quantitatively, the behavioural responses of the 
cold-water snail Lymnaea stagnalis to optimal and to sublethal elevated temperature regimes. The more 
limited objectives of the preliminary study herein summarized were to ascertain the activity patterns 
of adult L. stagnalis: (1) at an optimal temperature of 20°C, (2) at a sublethal elevated temperature of 
30°C; (3) during light and dark phases at each of these 2 temperature regimes; and (4) to test for acclima- 
tion to elevated temperature with time. The choice of 20°C as the optimal temperature was based on 
experimental results obtained by E. G. Berry and Henry van der Schalie (pers. comm., 1969), who found 
that this temperature was close to the optimum for survival, growth and reproduction for L. stagnalis from 
northern Michigan. The sublethal elevated temperature, 30°C, is reasonably close to the thermal maximum 
of 35°C ascertained by the author for this population of L. stagnalis, as well as being a convenient tempera- 
ture since most biochemical reaction rates double with each 10°C increase in temperature. 

In this preliminary study, 10 snails were maintained at 20°C for 7 days and the temperature was then 
increased I o С per hour, a rate consistent with most normal heating records, to 30°C at which temperature 
the snails were maintained for an additional 7 days. The temperature was then again increased I o С per 
hour to the thermal maximum of 35° С and held at this temperature for 3 days, at the end of which time all 
the snails were dead. Throughout these 17 days, the activities of the snails were recorded on time-lapse 



Supported by a research grant (5 TI AI 41) from the National Institute of Allergy and Infectious Diseases, 
U. S. Public Health Service. 



396 PROC. FOURTH EUROP. MALAC. CONGR. 

film at the rate of 1 frame each 30 seconds. The variables measured were temperature, oxygen content, 
barometric pressure and food supply; the light regime was 12 hours light-12 hours dark. 

As a 1st step to interpreting behavioural responses, diurnal activity patterns: breathing, copulating, 
feeding, ovipositioning, resting and 4 forms of movement (crawling on substrate, floating, gliding on surface 
film and twisting at the surface with shell uppermost), as well as all snail interactions were analyzed for 
3 of the snails at 2 days of each temperature regime. Since the rate of acclimation to higher temperatures 
is usually rapid, frequently occurring in less than 24 hours (Brett, 1946), it was decided to compare the 
2nd day at each temperature, a time at which acclimation should not yet be complete and a later day, the 
6th day at each temperature, to ascertain if acclimation occurred with time. Such a form of acclimation 
would seem a logical adaptation since aquatic organisms are often rhythmic and should be adapted in 
phase with the normal day (Welch & Wojtalik, 1968) and with the progression of the seasons. 

A detailed analysis of the activity patterns of all 10 snails on the 1st day of the study had shown that 
sequences and rates of activity patterns of individual snails were so different as to preclude summing 
results or comparing activity patterns of different snails under different temperature regimes and to 
warrant the detailed analysis of the activity patterns of individual snails through various temperature 
regimes. 

Among the results suggested by this analysis of individual snails are: (1) that overall, the per- 
centage of time spent breathing increased with an increase in temperature; (2) that the percentage 
of time spent in breathing may be less at night under optimal temperature conditions, but that under con- 
ditions of sublethal elevated temperature this tendency may be reversed; (3) that the percentage of time 
spent in feeding, while greater in darkness by a factor of 2 to 3 under optimal temperature conditions, 
became markedly reduced under elevated temperature conditions, so that the percentage of time spent 
feeding under elevated temperature conditions was about the same for both the light and dark phases; (4) 
that the proportion of time spent in actual movement was usually between 60 and 65% throughout the diurnal 
cycle showing no change with increase in temperature; but (5) that the rate of change from one activity 
pattern to another was greatly accelerated by the elevated temperature regime; this was more marked on 
the 2nd day than on the 6th day (suggesting that, in this aspect, acclimation occurred with time), and 
moreover (6) that the increase in temperature induced a rhythmicity to certain of the activity patterns, 
chiefly the set: breathing - crawling - resting - crawling - breathing, so that the actual length of time spent 
in each of these individual activity patterns was relatively constant whether the set was repeated over a 
period of 15 minutes or over one of several hours; and (7) that under both temperature regimes, individual 
snails were observed to be able to distinguish and follow their own slime trails and that although this was 
observed rather often at 20°C it was a more pronounced occurrence at the elevated temperature, particu- 
larly with regard to the set of patterns: breathing - crawling - resting - crawling - breathing, where a 
snail would be observed repeatedly to follow its own trail between its resting place and the surface of the 
water. 

In order to interpret the above results in a more detailed manner, the activity patterns of more snails 
are being analyzed for the 4 days already discussed as well as for the 1st days at 20°C, 30°C and 35°C. 
Moreover, additional studies are now underway to determine the effects of constant versus fluctuating 
acclimation temperatures on the responses of Lymnaea stagnalis to a wide range of sublethal elevated 
temperatures. These studies are being conducted in a simulated stream and are the next step before taking 
these studies to an actual field situation. The results of these analyses will be computerized so that more 
complicated facets of behaviour such as sequential analysis of activity patterns, social interactions and 
their effect on copulation, and circadian rhythms may also be analyzed. 

REFERENCES 

BRETT, J. R., 1946, Rate of gain of heat-tolerance in goldfish (Carassius auratus). Univ. Toronto Stud. 

biol. Ser., 53; Publ. Ont. Fish Res. Lab., 64: 9-28. 
WELCH, E. B. & WOJTALIK, T. A., 1968, Some effects of increased water temperature on aquatic life. 

48 p. Tennessee Valley Authority, Division of Health and Safety, Water Quality Branch. 



MALACOLOGIA, 1973, 14: 397-400 

PROC. FOURTH EUROP. MA LAC. CONGR. 
ISLAND SIZE AND SPECIES DIVERSITY IN PACIFIC ISLAND LAND SNAILS 

Alan Solem 
Field Museum of Natural History, Chicago, Illinois, U.S.A. 

Recent years have seen the development of theoretical biogeography (see MacArthur 
& Wilson, 1967). Since Preston's demonstration of a close relationship between the 
size of an area and the number of species inhabiting it, 2 additional biogeographical 
concepts have become almost axiomatic. First, that faunas have a saturation level, 
a maximum number of species that can live in a particular place. Second, the Mac- 
Arthur-Wilson theory that areas will achieve faunal equilibrium, a balance between 
colonization by new species and some extinction among those already present. 

These propositions were developed using data from taxa that represent human 
introductions, that show rapid colonization and turnover rates, that have a low ratio of 
island size to species survival area, or where local speciation is absent or at a bare 
minimum. In their study of the Polynesian ant fauna, Wilson & Taylor (1967) showed 
that when only the tramp species, those introduced by commerce, were considered, 
the species -area model was highly predictive, but that inclusion of the native ants 
found on the islands of American and Western Samoa resulted in skewing the curve 
drastically upwards. 

The Pacific Island land mollusks show perhaps a 95% level of specific endemism, 
frequently with only 1 of 2 islands or even part of an island comprising the entire 
range of a species. Studying their patterns of species-area diversity permits examin- 
ing the situation under conditions of maximal local differentiation where colonization 
rates apparently are very low. In addition, the Pacific basin is both ancient and 
stable, with islands having been present since at least the mid-Mesozoic. While 
virtually none of the islands would have been present for the entire period, there have 
been specks of dry land present throughout this era and some islands may have a 
50,000,000 year history. Evidence from the deep core drillings on Bikini and Eniwetok 
has demonstrated that there has been more than 5,000' of subsidence in Micronesia 
since the beginning of the Tertiary, while sea floor mapping has revealed numerous 
sunken guyots that formerly were elevated stepping stones for dispersal. The great 
age of the area, high endemicity, and great local speciation present a considerable 
contrast to the very young islands with rapidly shifting faunas that were used to 
establish the basic theoretical concepts. 

Full testing of species-area diversity requires comprehensive sampling and study 
of the faunal elements concerned. Unfortunately, while comprehensive samples of 
the Pacific Island land snail fauna have been made, most of these have not been 
studied and reported on in the literature. For example, there are 31 described taxa 
of Hawaiian endodontoid land snails, but collections in the Bishop Museum contain 
199-205 species from Hawaii (Solem, unpubl.). Slightly less than l /б are recorded in 
the literature. Fortunately, several of the numerically most important taxa found on 
the Pacific Islands have been monographed or reviewed utilizing modern systematic 
concepts and collection resources. The Achatinellidae (Cooke & Kondo, 1960), Partu- 
lidae (Kondo, 1968), endodontoid taxa (Solem, in press), and the 2 limacoid families 
(Helicarionidae and Zonitidae, see H. B. Baker, 1938, 1940, 1941) were used in a 
comprehensive survey of species diversity on many islands. 

In addition, there are some islands whose fauna has been monographed or from which 
sufficiently extensive collections were available that the total land snail diversity 

(397) 



398 



PROC. FOURTH EUROP. MALAC. CONGR. 

TABLE 1. Species-area relationships for selected islands 



Island 


Area in 
miles 2 


Land snail 
families 


Observed species 
diversity 


Calculated diversity 


S=10A°- 27 


S=18.6A°- 63 


Lord Howe 


5 


9 


51 


15 


51 


Rapa 


14.2 


8 


100 


21 


99 


Upolu 


430 


10 


44 


51 


848 


Oahu 


604 


8 


395 


56 


1,045 


Viti Levu 


4,011 


10 


58 


94 


3,464 



TABLE 2. Me 


an 


number of land 


snail species 


Island area 




under 1,000' 


over 1,300' 


in miles 2 




elevation 


elevation 


4.9-8 




9.5 


34.3 


10-15 




9.5 


31.5 


18-28 




12.5 


20.0 


34-60 




7.0 


16.5 


100-225 




8.0 


21.8 



could be estimated with some accuracy. These include Upolu, Western Samoa (Garrett, 
1887 and collections made by the author in 1965), Rapa (collections in the Bernice P. 
Bishop Museum), Lord Howe Island off Australia (Iredale, 1944 as modified by study 
of collections made in 1963 and type material in the Australian Museum, Sydney to 
reduce Iredalean species multiplication), Viti Levu, Fiji (Germain, 1932 and collections 
made in 1971), and Oahu, Hawaiian Islands (data from many sources). 

The contrasts in relative species abundance for the well sampled islands are 
striking, as is their lack of conformity to the predictive formula S_ = CA -(where S is 
the number of species, C_ a variable constant, A refers to island area, and z^ is a 
second variable constant). In its most frequently used form, Ç is 10 and z_is 0.27. 
Table 1 lists the islands, their areas, the number of native land snail families present, 
the observed species abundance, the abundance predicted by S = 10A - 27 , and the 
numbers predicted by an adjustment in both C_ and z so that the observed species 
numbers for both Rapa and Lord Howe Island would be produced. It is obvious that 
the relative abundance of species does not correlate with island area. This difference 
cannot be attributed to a new faunal element wiping out forms that are an important 
group elsewhere. Both Viti Levu and Upolu have the prosobranch family Poteriidae; 
Lord Howe Island, Upolu and Viti Levu have the prosobranch family Diplommatinidae; 
Lord Howe and Viti Levu have the Bulimulidae; and Succineidae are found on both 
Upolu and Oahu. Otherwise the family groups are essentially the same. 

If Rapa and Lord Howe Island are assumed to be saturated, then the other islands 
are markedly "underdiversified. " 

The question of correlation between island factors and snail diversity does not lie 



SOLEM 399 

in terms of area alone. By using data from the recently monographed families, it 
was possible to gain information of partial species diversity for 57 Polynesian and 
Micronesian islands (excluding the Hawaiian chain). When the islands were grouped by 
size, there was a 3 step diversity: under 4 square miles, low diversity; 4.9-225 
square miles, a higher, but unchanging level of diversity; 400-4,000 square miles, 
a slight increase over the 2nd stage. When the islands were grouped by elevation: under 
700 feet, low diversity; over 920 feet, high diversity; over 4,300 feet, slight increase 
in diversity probably associated with these islands being 10 times the size of those 
in the next lower group. 

If island area and elevation are combined in a single analysis (Table 2), it is evident 
that the primary correlations indicative of high land snail species diversity are: 1) 
elevation of more than 1,300 feet; and 2) island size between 4.9 and 15 square miles. 
Two additional correlations can be made: 1) islands nearer the New Guinea-Indonesian 
core region have markedly lower diversity than islands of equal size located farther 
out in the Pacific; and 2) more isolated islands such as Lord Howe, Mangareva and 
Rapa have far greater species level diversity than islands of the same size located 
within an archipelago. 

It is quite probable that prédation by the native ants on Viti Levu and Upolu has 
limited snail diversity, since on Oahu and many Polynesian islands, which lacked any 
native ants, it is evident that the introduced ants have decimated the native fauna. 
The meaning of the approximately 1,000 foot elevation triggering higher diversity 
probably relates to moisture supplies. Higher islands have proportionately much 
greater rainfall than do lower islands, and islands of under 1,000 feet elevation may 
have too little or too infrequent rainfall. The isolated islands may attain greater 
diversity because of less frequent colonization by either competitors or predators. 
Similarly, the greater land snail diversity on islands 4.9-15 square miles in size may 
result from absence of competition from some nonmolluscan group or by the absence 
of some predators that require more than 15 square miles to maintain a breeding 
population. 

All of the above speculations require field observations and experimental data for 
substantiation or refuting. They may serve to provide a stimulus for further work 
on the problem of explaining the very different patterns of snail diversity found on 
Pacific Islands from that predicted by the species-area model and equilibrium theory. 

LITERATURE CITED 

BAKER, H. В., 1938, Zonitid snails from Pacific Islands. Part 1. Bull. Bernice P. 

Bishop Mus., 158: 1-102. 
BAKER, H. В., 1940, Zonitid snails from Pacific Islands. Part 2. Bull. Bernice P. 

Bishop Mus., 165: 103-201. 
BAKER, H. В., 1941, Zonitid snails from Pacific Islands. Parts 3 and 4. Bull. 

Bernice P. Bishop Mus., 166: 202-370. 
COOKE, C. M. & KONDO, Y., 1960, Revision of Tornatellinidae and Achatinellidae 

(Gastropoda, Pulmonata). Bull. Bernice P. Bishop Mus., 221: 1-303. 
GARRETT, A., 1887, The terrestrial Mollusca inhabiting the Samoa or Navigator 

Islands. Proc. Acad, natur. Sei. Philad., 1887: 124-153. 
GERMAIN, L., 1932, La Faune Malacologique des Ues Fidji. Ann. Inst. Oceanogr., 

Monaco, 12(2): 39-63. 
IREDALE, Tom, 1944, The land Mollusca of Lord Howe Island. Austr. J. Zool., 10(3): 

299-334. 
KONDO, Y., 1968, Partulidae: Preview of anatomical revision. Nautilus, 81(3): 73-77. 
MACARTHUR, R. H. & WILSON, E. O., 1967, The theory of island biogeography. 



400 PROC. FOURTH EUROP. MALAC. CONGR. 

Princeton University Press. 203 p. 
SOLEM, A., in press, Endodontoid land snails from Pacific Islands. Parts 1 and 2. 

Field Museum of Natural History. 
WILSON, E. O. & TAYLOR, R. W., 1967, An estimate of the potential evolutionary 

increase in species density in the Polynesian ant fauna. Evolution, 21(1): 1-10. 



MALACOLOGIA, 1973, 14: 401-408 

PROC. FOURTH EUROP. MALAC. CONGR. 

POSSIBLE COMPETITIVE DISPLACEMENT AND EVIDENCE OF 
HYBRIDIZATION BETWEEN TWO BRAZILIAN SPECIES OF PLANORBID SNAILS 1 

F. S. Barbosa 

The World Health Organization, Parasitic Diseases 
Division of Communicable Diseases, Geneva, Switzerland 

ABSTRACT 

Occasional introduction of Biomphalaria straminea in an area known for 
several years to be inhabited exclusively by B. glabrata, allowed the study of 
the behaviour of these closely related planorbid species competing in the same 
body of water. B. glabrata was totally eliminated and substituted by B. stram- 
inea within a period of 3 years. Four mixed forms collected in the area were 
interpreted as inter-species hybrids. These however had disappeared by the 
following year, thus showing their inability to perpetuate themselves in nature. 
The substitution of B. glabrata by B. straminea was considered as a possible 
case of competitive displacement, although only suggestions were made as to 
the forces which may have favoured B. straminea. 

INTRODUCTION 

The Planorbidae are freshwater snails living in a variety of habitats around the 
world. Those belonging to the genus Biomphalaria are limited in their distribution to 
the African and American continents and to South West Asia. In the Americas, Biom- 
phalaria distribution ranges from the southern part of North America, through Central 
America, on down to the southern part of South America. On this continent 17 Biom- 
phalaria species have been recognized, most of them occurring in the tropical regions. 
These snails have received special attention since some of them serve as intermediate 
hosts of schistosomiasis mansoni, an important human disease in several tropical 
regions of the world. 

In north-eastern Brazil, the 2 snail intermediate hosts of Schistosoma mansoni are 
Biomphalaria glabrata (Say) and B. straminea (Dunker). B. glabrata is found in many 
islands of the West Indies, and in the north and east of South America (Venezuela, 
Surinam, French Guyana and Brazil), between the latitudes 20 °N and 26°S. B. strami- 
nea exists in Paraguay, Venezuela, the Guyanas and Brazil reaching to about 20°S. 

Biomphalaria glabrata and B. straminea differ from each other in their morpholo- 
gical features. The differences are few but conspicuous. The genitalia and the renal 
tube present reliable means of differentiation between the 2 species. The following 
specific characteristics are considered of particular value. The vagina of B. glabrata 
shows a prominent pouch while that of B. straminea presents a typical vaginal cor- 
rugation. The ovotestis diverticula in B. glabrata are predominantly trifúrcate but 
may be divided into from 2 to 5 branches and only exceptionally may be unbranched. 
In B. straminea, the ovotestis diverticula are usually unbranched, though sometimes 
bifurcate and occasionally trifúrcate. This species lacks a renal ridge which is pre- 
sent in B. glabrata. Conchological features are of limited value because they are 



^-This study was carried out by the Research Center "Aggeu Magalhâes, " Recife, Brazil. 

(401) 



402 PROC. FOURTH EUROP. MALAC. CONGR. 

less reliable than the anatomical ones for species identification purposes. 

Although Biomphalaria glabrata and B. straminea occur in the same areas of the 
coastal region of the State of Pernambuco, these closely related species are very 
seldom found in the same body of water (Barbosa & Olivier, 1958). 

Interspecific crosses have been obtained in the laboratory between allopatric as 
well as sympatric species of planorbid snails. It has also been shown that the 2 
species dealt with in this paper are able to hybridize under laboratory conditions 
(Barbosa, 1960 and PAHO/WHO, 1968). 

The present study was undertaken to determine the circumstances in which isolating 
mechanisms could be broken down in nature, and to investigate the possible significance 
of this fact. Much knowledge was gained on the behaviour of the 2 species when com- 
peting in the same body of water. The occasional occurrence of certain conditions 
were found to be of particular value to the present studies. 

GENERAL INFORMATION ON THE STUDY AREA 

The geographical region known as north-east Brazil includes different physio- 
graphical zones. The physiography of Pernambuco is more or less the same as that 
of north-east Brazil. It has a narrow coastal zone, followed by a zone of low rolling 
hills which is about 50 to 80 km wide and is continued by a high inland plateau. The 
littoral zone is just a narrow, sandy strip of land, covered by typical vegetation, and 
spotted by dunes and mangrove areas. The middle zone was originally covered by 
tropical forests, now mostly destroyed. The inland plateau, called caatinga, is a 
rough, stony, semi -arid zone with short, spiny vegetation having deciduous leaves. 
Limited zones with a specific type of vegetation are called cerrados. 

The temperature in the littoral and forest zones averages about 27°C all the year 
round, and over a period of 14 years the mean monthly rainfall as given by Olivier & 
Barbosa (1955) has been : March 156 mm; April 253 mm; May 374 mm; June 293 mm; 
July 215 mm; and August 161 mm. During the remainder of the year the average 
monthly rainfall varies from 26 mm to 66 mm. This shows the marked seasonal 
rainfall cycle in these regions. 

Recife, the capital of the state of Pernambuco, is situated on the seacoast, at 8°3*S 
and 34°51'W. The present study was carried out in a limited area of about 6 km 2 
situated on the outskirts of Recife. This low-lying area is mostly covered by coarse 
grass though parts are irrigated for the cultivation of vegetables. A slow-moving 
stream crosses it from west to east in the direction of the mangrove swamps. The 
stream has its source about 6 km inland on a low hill. 

At the beginning of the dry season, i.e., usually by the end of September, the water 
level falls. About a month later there is no more standing water in the fields and at 
this time aestivating snails, protected by grass or debris, were easily found on the 
soil. During the wet season, usually from May to September, the fields are filled 
with water and at the end of the rainy season large populations of Biomphalaria 
glabrata were found all over the area. Most of the active snails were found in the 
irrigation ditches. 

METHODS 

From 1952 to 1955 several routine checks were made of the entire area, although 
at irregular intervals, in order to collect snails needed in different types of laboratory 
work. Biomphalaria glabrata was the only species found in the area. However, in 
November 1956 a small colony of B. straminea was accidentally found thriving in the 
upper part of the stream crossing the study area, thus providing the author with the 



BARBOSA 



403 



SNAIL 



VAGINA 



В. 

glabrata 



В. 
straminea 



со 
Ci 



OVOTESTIS 



lateral view Ге°Л%п 





В 



straminea 
type 





glabra ta 
type 



RENAL TUBE 
proximal parr 




rer 




mu 



glaàrata 
type 



¡VQ 

mixed form 



straminea 
type 



straminea 
type 



FIG. 1. Comparison oí the anatomy oí BiomphaLaria glabrata and B. straminea and their hybrids, 
mu, meatus of ureter; pv, pulmonary vein; rer, renal ridge; rv, renal vein; sp, spermathecal 
sac; ut, uterus; va, vagina; vc, vaginal corrugation; vp, vaginal pouch. 

opportunity of studying the balance between the 2 snail populations. Working on the 
assumption that the heavy rains of the next wet season would carry the snails down- 
stream, the area was kept under particularly close observation. From 1957, when 
the 1st specimens of B. straminea were found in the study area, until 1960, snails 
were systematically collected every year during the month of September. A random 
sample of 10% of the snails collected was dissected for anatomical studies in 1957 
and 1958. This figure was raised to 50% in 1959 and 1960. The snail densities were 
measured once a year during the month of September, just after the rainy season 
when the snail populations attain higher levels. During 4 weeks (20 working days) 2 
carefully trained field workers covered the entire area and collected the snails by 
using a standard snail scoop consisting of a large perforated metal cup which was 
dipped into the water every 10 steps down to the bottom of the ditches. The number 
of snails thus collected was recorded per dip and their average number could then be 
calculated. Results are presented as "snails per dip." To determine the infection 
rates, the snails were exposed to a strong source of artificial light for 1 hour during 
the appropriate time of day, after which they were examined for cercariae. 



404 



PROC. FOURTH EUROP. MALAC. CONGR. 



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BARBOSA 405 

RESULTS 

Following the discovery of the 1st small colony of Biomphalaria straminea in 
November 1956, the snails were seen migrating to small ditches in the area which 
drained to the stream's head. At the beginning of 1957 several well established colo- 
nies of B. straminea were breeding in the ditches all around the head of the stream. 
The 1st systematic collection made in September 1957 revealed that B. straminea 
had arrived in the low-lying area inhabited by B. glabrata. Out of 383 snails collected 
in the area and examined, 38 were B. straminea. It was furthermore observed that 
all 38 specimens of B. straminea came from the same ditch. 

During the same period of the following year (1958), 350 snails were examined. 
Biomphalaria straminea was now the predominant species and was found throughout 
the area. Special attention was paid to the possibility of encountering intermediate 
forms. The results were as follows: 337 B. straminea, 9 B. glabrata and 4 intermediate 
forms. The intermediate forms were submitted to careful morphological studies, 
which took into consideration the 3 main anatomical characteristics known to be of 
primary importance in distinguishing the 2 species, i.e., the external surface of the 
vagina, the branching diverticula of the ovotestis and the upper surface of the renal 
tube. Two types of mixed forms were seen: A showed a vagina of the B. straminea 
type and glabrata -like ovotestis and renal tube, while В exhibited a vagina of mixed 
type (i.e., with corrugation plus a pouch) and ovotestis and renal tube of the straminea 
type (Fig. 1). 

In 1959 and 1960 only typical Biomphalaria straminea were found in the area. For 
those 2 years random sampling of the snails collected having been increased to 50%, 
1202 and 1892 snails were examined respectively, and the 1959 results were confirmed 
by those obtained in 1960. 

Table 1 gives the results for the 4 years 1957-1960. 

DISCUSSION 

The substitution of a natural population by another, even within restricted limits as 
in the present study, shows that the balance between the 2 populations was broken in 
favour of 1 of them. This is a well-known phenomenon which especially occurs when 2 
closely related species are involved. The results of the study suggest a competitive 
displacement of Biomphalaria glabrata by B. straminea. The ecology of these planor- 
bid snails is not sufficiently known to provide a satisfactory explanation for the gradual 
replacement of B. glabrata by B. straminea. Both species are found in a variety of 
habitats and presumably have similar or identical requirements. The fact that these 
2 species, although inhabiting the same region, are never or very seldom found to- 
gether in the same breeding place (Barbosa & Olivier, 1958) can be explained by the 
old principle revised by De Bach (1966): "Different species which co-exist indefinitely 
in the same habitat must have different ecological niches; this is, they must not be 
ecological homologues." Although the above statement remains true as an ecological 
principle some evidence has been brought to show that it cannot be generalized. It 
has been shown that when the environment is not completely uniform in space or in 
time, prolonged or even indefinite co-existence of competitors is possible. 

Pielou (1969) had recently demonstrated that mathematically the indefinitive co- 
existence of the competing species in a state of stable equilibrium is possible and 
that, theoretically, co-existence of ecological homologues can happen. On the other 
hand the well-known classical laboratory experiments of Park (1954) with mixed 
populations of the flour beetles Tribolium confusum and T. castaneum are interpreted 
by Pielou (1969) as an example of competitive displacement between species which 



406 PROC. FOURTH EUROP. MALAC. CONGR. 

are not ecological homologues. 

Although in the present study the phenomenon can be tentatively explained in terms 
of competitive displacement, the forces favouring Biomphlaria straminea remain 
unknown. Two possibilities can be suggested to explain the break of the population 
stability of B. glabrata: 1) B. straminea is much less susceptible to infection with 
Schistosoma mansoni, and this human trematode, which was prevalent in the area, 
has a definite killing effect on the snails it infects; 2) It has been suggested that B. 
straminea is more resistant to dessication than B. glabrata, and the area has a natural 
cyclic dry season. The above 2 factors might have favoured B. straminea in the course 
of the competitive displacement. 

The fact that natural selection may favour an unsusceptible strain of the snail host 
living together with a susceptible one was pointed out by Hubendick (1958), although at 
that time he considered this no more than a theoretical possibility. Very recently 
Richards (1970), studying the genetics of Biomphalaria glabrata in the laboratory, 
suggested that the combination of unsusceptibility to Schistosoma mansoni with 
drought-resistance could speed up the process of favourable selection in temporary 
habitats. Commenting on the above paper Wright (1971) states that such studies 
provide a most important basis for a possible method of biological control of schisto- 
somiasis, although he mentions several potential complications that may occur in 
nature from a purely malacological view of the problem. In the present paper field 
evidence is brought to show that a snail species combining partial susceptibility to 
S. mansoni with higher drought-resistance can displace in a temporary habitat another 
species known to be highly susceptible and less resistant to drought. 

The genetic relationships among the planorbid snails are not completely understood. 
Planorbid snail species are known to hybridize under laboratory conditions. In fact it 
has been shown that in this group interspecific crossings are not uncommon. Experi- 
mental crosses between Biomphalaria straminea and B. glabrata from the same region 
with the production of fertile offspring, have been recorded (Barbosa, 1960 and РАНО/ 
WHO, 1968). After the prolonged contact of these 2 species in nature, few specimens 
were found to show the mixed morphological characteristics of interspecific hybrids. 
Although, in the present instance, the genetic barrier could not completely prevent 
interspecific hybridization, it is evident that an effective barrier between the 2 species 
does exist, since the natural hybrids did not perpetuate themselves in nature. The 
occurrence of occasional hybrids between sympatric species is not a sufficient argu- 
ment to place in doubt the validity of regarding their parent forms as distinct species. 

The only other instance of mixed forms of planorbid species found in nature is that 
reported by Barbosa (1964) in the State of Rio de Janeiro, Brazil. Out of 498 speci- 
mens of Biomphalaria tenagophila collected in the area, 2 showed a typical renal ridge 
which is considered as a specific feature of B. glabrata. In 8 other specimens poorly 
developed renal ridges were found. These observations, although difficult to interpret, 
suggest the possibility of natural hybridization between the 2 species. 

Methods of vector control other than the application of pesticides have lately been 
coming to the attention of public health workers. The possibility of using different 
predators, parasites and competitors in the control of the snail intermediate hosts of 
schistosomiasis is still under consideration. A review of biological control of trema- 
tode diseases was recently made by Wright (1968). Although investigations have not 
been encouraging, some optimistic reports are coming from Puerto Rico (Ruiz-Tiben, 
Palmer & Ferguson, 1969) on the ability of Marisa cornuarietis to act as both preda- 
tor and competitor of Biomphalaria glabrata, the local intermediate host of Schisto- 
soma mansoni. A recommendation that studies be continued to assess the value of 
biological control of the snail intermediate hosts of the schistosomes was recently 
made by a WHO Expert Committee (1967). 



BARBOSA 407 

The present paper has shown that a population of 1 species of planorbid snail was 
accidentally replaced by another. This offers wider perspectives for studies on inter- 
action between freshwater snail species. The phenomenon is not rare in nature (De 
Bach, 1966) and, besides its basic importance in ecology and evolution, may have sub- 
stantial significance in the practical field of schistosomiasis control. If we are, on the 
one hand, largely ignorant of the requirements and behaviour of the planorbid snails, 
of their homologies and heterogeneities, in other words of their ecological niches, we 
do know, on the other hand, that some species of Biomphalaria are very closely 
related to one another both morphologically and genetically (Barbosa, 1960 and РАНО/ 
WHO, 1968). In connexion with the foregoing we wish to stress the need for carrying 
out basic ecological and genetic studies in order to define the characteristics of the 
natural populations of snail intermediate hosts of schistosomiasis. 

RESUME 

POSSIBILITE DE DEPLACEMENT COMPETITIF ET 

MISE EN EVIDENCE D'HYBRIDATION ENTRE DEUX ESPECES BRESILIENNES 

DE MOLLUSQUES PLANORBIDES 

L'introduction occasionnelle de Biomphalaria straminea dans une région connue 
depuis des années comme habitée exclusivement par B. glabrata a permis l'étude du 
comportement de ces deux espèces très voisines de Planorbidés en compétition dans 
la même pièce d'eau. B. glabrata a été totalement éliminé et remplacé par B. strami- 
nea en moins de trois ans. Quatre formes mixtes récoltées dans la zone de l'étude 
ont été considérées comme des hybrides; toutefois, elles ont disparu au cours de 
l'année suivante, prouvant ainsi leur incapacité à se reproduire d'elles-mêmes dans 
les conditions naturelles. Le remplacement de В . glabrata par В . straminea est 
considéré comme un cas probable de déplacement compétitif et des hypothèses sont 
formulées, concernant les facteurs qui ont pu favoriser B. straminea. 

REFERENCES 

BARBOSA, F. S., 1960, Proven and potential vectors of the trematode Schistosoma 

mansoni in South America. Rev. bras. Biol., 20: 183-190. 
BARBOSA, F. S., 1964, The renal ridge, a disputed feature of the anatomy of the 

planorbid snail Australorbis tenagophilus . Revta. Inst. Med. trop. S. Paulo, 6: 

64-70. 
BARBOSA, F. S. & OLIVIER, L. J., 1958, Studies on the snail vectors of bilhaziasis 

mansoni in North-eastern Brazil. Bull. Wld. Hlth. Org., 18: 895-908. 
DE BACH, P., 1966, The competitive displacement and coexistence principles. A. 

Rev. Ent., 11: 183-212. 
HUBENDICK, В., 1958, A possible method of schistosome -vector control by competi- 
tion between resistant and susceptible strains. Bull. Wld. Hlth. Org., 18: 1113- 

1116. 
OLIVIER, L., 1956, Observations on vectors of schistosomiasis mansoni kept out of 

water in the laboratory. J. Parasitol., 43: 137-146. 
OLIVIER, L. & BARBOSA, F. S., 1955, Seasonal studies on Australorbis glabratus 

Say from two localities in Eastern Pernambuco, Brazil. Publçoes avuls. Inst. 

Aggeu Magalháes, 4: 79-103. 
РАНО /WHO, 1968, A guide for the identification of the snail intermediate hosts of 

schistosomiasis in the Americas. Scientific publication No. 168. 
PARK, T., 1954, Experimental studies of interspecies competition. H. Temperature, 



408 PROC. FOURTH EUROP. MALAC. CONGR. 

humidity, and competition in two species of Tribolium. Physiol. Zool., 27: 177- 

238. 
PIELOU, E. C, 1969, An introduction to mathematical Ecology. Wiley -Inter sei. 

Pubis., New York, U.S.A. 
RICHARDS, C. S., 1970, Genetics of a molluscan vector of schistosomiasis. Nature, 

227: 806-810. 
RUIZ-TIBEN, E., PALMER, J. R. & FERGUSON, F. F., 1969, Biological control of 

Biomphalaria glabrata by Marisa cornuarietis in irrigation ponds in Puerto 

Rico. Bull. Wld. Hlth. Org., 41: 329-333. 
WHO, 1967, Epidemiology and control of schistosomiasis. Report of a WHO Expert 

Committee. Technical Report Series No. 372, Geneva. 
WRIGHT, С. A., 1968, Some views on biological control of trematode diseases. 

Trans. Roy. Soc. trop. Med. Hyg., 62: 320-324. 
WRIGHT, C. A., 1971, Comments on the paper "Genetics of a molluscan vector of 

schistosomiasis" by C. S. Richards. Trop. Dis. Bull., 68: 333-335. 



MALACOLOGIA, 1973, 14: 409 

PROC. FOURTH EUROP. MALAC. CONGR. 

EASTWARD AND WESTWARD DISPERSAL OF TROPICAL PROSOBRANCH 
LARVAE ACROSS THE MID-ATLANTIC BARRIER 

Rudolf S. Scheltema 

Woods Hole Océanographie Institution, Woods Hole, Massachusetts, U.S.A. 02543 

ABSTRACT 1 

The dispersal of larvae over long distances depends upon the velocity of ocean currents and the duration 
of planktonic development. Plankton collections made throughout the tropical Atlantic show that the 
larvae of shoalwater species from the continental shelf are regularly carried for long distances, and that 
they can be found in every major ocean current. The larvae of stenothermal tropical forms are carried 
westward from West Africa on the North and South equatorial currents and eastward from Brazil along 
the equatorial undercurrent. The genus Bursa is an interesting example, as its teleplanic forms are 
commonly found in both the tropical surface and undercurrent systems. An estimate of the duration of 
larval life and a knowledge of the current velocity suggest regular exchange of Bursa larvae between the 
continents of South America and Africa. 



*The complete text is published under the title "Eastward and Westward dispersal across the tropical Atlan- 
tic Ocean of larvae belonging to the genus Bursa (Prosobranchia, Mesogastropoda, Bursidae)." Inter. Rev. 
Gesamten Hydrobiol., 57(6): 877-887. 



MALACOLOGIA, 1973, 14: 409 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE DISTRIBUTION OF THE LAND MOLLUSCS IN THE UPHEAVAL AREA 
IN THE QUARKEN, AN ARCHIPELAGO IN THE GULF OF BOTHNIA 

Ilmari Valovirta 

Zoological Museum, University of Helsinki, Finland 

SUMMARY 1 

The study area is right at the centre of the land upheaval area in the Northern Baltic, where the earth's 
crust is rising at a rate of ca. 100 cm a century. The upheaval phenomenon is most evident in the shallow 
sea area, where new islets continually appear and the area of the existing islands enlarges. This study 
concerns the distribution and dispersal of 38 land mollusc species living on the islands, which have risen 
out of the sea. What are the patterns of age diversity, area diversity and isolation diversity at the species 
and population levels? What are the 1st species to occupy the islets as they emerge, and how quickly can 
they do so? As the age of an island can be calculated, it is possible to tell the maximum time that a land 
mollusc species needs to reach the island by some means of passive dispersal (but allowing for the gap 
between the emergence of the island and the time at which it provides the minimal requirements of the 
species). There are 385 sample plots on the study area, and the number of mollusc specimens collected 
is over 50,000. 



A detailed account of this study will be published in "Annales zoologici Fennici. 



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MALACOLOGIA, 1973, 14: 411-413 

PROC. FOURTH EUROP. MALAC. CONGR. 

THE EUROPEAN INVERTEBRATE SURVEY 

John Heath 

Biological Records Centre, Monks Wood Experimental Station, Abbots Ripton 

Huntingdon, England 

The value of detailed distribution maps of species as aids to nature conservation, 
ecology and natural history was first clearly demonstrated when the "Atlas of the 
British Flora" was published in 1962. The methods developed for the production of 
these botanical maps have now been refined and are being used by the Biological 
Records Centre, which is part of the Nature Conservancy's Monks Wood Experimental 
Station near Huntingdon, for the preparation of maps of various animal groups. For 
the maps of Britain the basis of all the schemes is to indicate by means of a conven- 
tional symbol the presence of each species in each 10 km square of the appropriate 
map grid, i.e., British National Grid, Irish Grid or Universal Transverse Mercator 
Grid. The use of grid squares means that comparisons of one area with another are 
always made using units of equal size. As there are 3600 such squares in the British 
Isles the mapping of a group of 100 species could involve the handling of upwards of 
2 million individual records. In addition to field records, museum and literature 
records are frequently used as supporting data. Each record of a particular species 
is stored on magnetic tape at the Atlas 2 computer centre in Cambridge. The records 
are entered and access to them is by means of a remote teletype terminal at Monks 
Wood. For map making a special set of 80 column punch cards is prepared by the 
computer. These cards then produce the map mechanically on a specially modified 
electric typewriter (IBM 866) controlled by an automatic card reading machine 
(IBM 836). 

In planning a mapping scheme, whether it be for a continent the size of Europe, or 
a small island, 2 main factors govern the size of the recording area. The 1st con- 
sideration must be the fineness of detail required to give a proper picture of the 
distribution of the organism concerned, and the 2nd is the number of recorders 
available for the survey. As the maps must obviously be as up-to-date as possible, 
the survey period should be kept as short as possible. For Britain, it is considered 
that 10 years is a realistic time for a survey involving 1,000 recorders, i.e., with 
each recorder being responsible for an average of four 10 km squares. With smaller 
areas in Britain the tetrad (2 km x 2 km square) has been adopted by botanists for 
county floras, and entomologists are using a square of 5 km x 5 km for such mobile 
insects as the Lepidoptera. At the county (province, canton) level these are considered 
to give sufficient detail for the pattern of distribution to be resolved. However, on 
small islands where there is a great diversity of habitat it may be desirable to use a 
1 km or even 500 m square as the standard recording unit. 

The collection of data for the British National schemes is usually organised by the 
relevant national biological society, e.g., the Conchological Society is responsible for 
the mapping of Mollusca, whilst the Biological Records Centre advises, processes the 
data, and produces the maps. When organizing field recording, the aim should be the 
compilation of species lists, as complete as possible, for each of the squares being 
used as the basis of the scheme. For this purpose 3 special cards can be used, 
namely 1) a Field Card, normally 20 cm x 13 cm, on which is printed the species list 
of the group concerned in alphabetical order, with the names abbreviated if necessary. 
In use the recorder completes 1 of these cards for each square by crossing through 

(411) 



412 PROC. FOURTH EUROP. MALAC. CONGR. 

the name of the species being recorded; 2) an Individual Record Card (a specially 
printed punch card which can be handled directly by the data processing machinery) 
on which 1 species can be recorded from 1 square, together with other information, 
e.g., status, rarity, stage, etc. and 3) a One Species Card, again 20 cm x 13 cm in 
size, on which 1 species can be recorded from any number of squares. For each 
square a Field Card can be used as a Master Card on which all the records received 
from the square can, after checking, be summarized. In this way duplication can be 
eliminated. The distribution maps can then be plotted either mechanically, or by hand 
directly from the master cards. A unique feature of this method is that at the same 
time situation maps can be produced showing the completeness of the survey by indi- 
cating (using a suitable scale) the number of species recorded in each square. Thus 
meaning can be given to incomplete data. 

When using this method all the recorder is asked to do is to record the presence of 
the species in a square printed on a map of the area. No counting of individuals or 
other sophisticated recording techniques are needed and therefore it gives a standard 
method which can be used by anyone able to identify the organisms being surveyed. 
This considerably reduces the sampling errors which frequently complicate the asses- 
ment of the results of biological surveys. To ensure absolute accuracy for every 
record is impossible, but checks can be made by 1) referring records to a local expert 
who will indicate those which require verification, 2) by specialist examination of 
material from the critical groups and 3) by noting and checking outlying records when 
maps are produced. Lists of critical species have been prepared for all the groups 
which are being surveyed by the Biological Records Centre, and Guides to the Identi- 
fication of these, containing illustrated keys, are being produced. Additionally 
training courses for amateur naturalists are organised each year which provide basic 
instruction in the techniques of identification and field sampling methods. 

These surveys also result in the identification of those species in need of protection. 
Repeat surveys carried out at regular, e.g., 5 year, intervals enable changes in 
distribution and status to be shown. With these sort of data a much more effective 
case can be made for the introduction of conservation legislation by the authorities 
than with existing subjective assessments of possible threats to wildlife. 

The success of these British schemes resulted in 1965 in the setting up of the 
international project for mapping European vascular plants with a secretariat in 
Helsinki and in 1969 the initiation jointly by the Biological Records Centre and Pro- 
fessor Jean Leclercq at Gembloux, Belgium of the European Invertebrate Survey. 

The objectives of this are: 1) the compilation of lists of verified Zoogeographie 
data which can be used for map making and statistical studies; 2) the publication and 
interpretation of distribution maps based on theU.T.M. grid, with 50 km squares being 
used for all Europe and 10 km or 5 km squares for those countries and regions where 
more detailed surveys have been carried out; and 3) to encourage the setting up of 
records centres in all countries. 

Already 4 parts of the Atlas Provisoire des Insectes de Belgique and 1 part of the 
Atlas Provisoire des Arthropodes non Insectes de Belgique and the 1st part of the 
Provisional Atlas of the Insects of the British Isles have been published. Records 
centres have been or are being set up in France, Belgium, Netherlands, Luxembourg, 
Germany, Denmark, Sweden and Finland. The Biological Records Centre at Huntingdon 
together with Prof. Leclercq' s department at Gembloux are acting as co-ordinating 
centres. All invertebrate zoologists, both professional and amateur, are invited to 
participate in this project. Of all the group of plants and animals the mollusca are 
probably the easiest to survey and I hope that one of the results of this conference 
will be the setting up of an integrated European scheme to map this group. 



HEATH 413 

REFERENCES 

ALFORD, D. V., 1970-71, Bumblebee Distribution Maps Scheme. Guide to the British 

Species. Parts 1-4. Entomologists Gaz., 21: 109-116; 22: 29-36, 97-102, 229-234. 
HEATH, J., et al., 1969-71, Lepidoptera Distribution Maps Scheme. Guide to the 

critical species. Parts 1-4. Entomologists Gaz., 20: 89-95, 263-296; 21: 102-105; 

22: 19-22, 109-110. 
HEATH, J., 1971, The European invertebrate survey. Acta Ent. Fenn., 28: 27-30. 
HEATH, J., ed., 1970, Provisional Atlas of the insects of the British Isles. Part 1. 

Lepidoptera Rhopalocera. Nature Conservancy, Lond. 
LECLERCQ, J., ed., 1970, Atlas Provisoire des insectes de Belgique. Cartes 1 à 100; 

101 à 200. Fac. Sei. Agr., Gembloux. 
LECLERCQ, J., ed., 1971, Atlas provisoire des insectes de Belgique. Cartes 201 à 300; 

301 à 400. Fac. Sei. Agr., Gembloux. 
LECLERCQ, J. & LEBRUN, P., eds., 1971, Atlas Provisoire des Arthropodes non 

insectes de Belgique. Cartes 1 à 24. Fac. Sei. Agr., Gembloux. 
PERRING, F. H., 1971, The Biological Records Centre - a data centre. Biol. J. Linn. 

Soc. Lond., 3: 239-243. 
PERRING, F. H. & WALTERS, S. M., 1962, Atlas of the British flora, Nelson, Lond. 



MALACOLOGIA, 1973, 14: 414 

PROC. FOURTH EUROP. MALAC. CONGR. 
VORSCHLÄGE ZUR ERFASSUNG DER MITTELEUROPÄISCHEN MOLLUSKEN 

H. Ant 

Hamm, Deutschland 

ZUSAMMENFASSUNG 

Die faunistische Erforschung Europas ist in vielen Gebieten und für manche Tiergruppen schon recht 
weit gediehen. Die zunehmende Einengung natürlicher Biotope lässt es geboten erscheinen, eine genaue 
Erfassung aller Arten und ihrer Verbreitung so schnell wie möglich in Angriff zu nehmen. Dieses Problem 
ist in Europa bereits verschiedentlich erörtert worden; auch sind Ansätze für eine Kartierung der Wirbel- 
losen vorhanden. Es sei erinnert an die Floristische Kartierung Mitteleuropas, die Erfassung der 
Wirbellosen in England und Frankreich sowie der Beginn einer Kartierung und Erfassung der Mollusken 
Englands. 

Es scheint daher dringend erforderlich zu sein, dass die UNITAS MALACOLOGICA EUROPAEA ein 
allgemeines Programm zur Erfassung aller europäischen Mollusken aufstellt. Hier wird vorgeschlagen: 
1, Zusammenarbeit der bereits tätigen Organisationen, Institutionen oder Privatpersonen; Bildung einer 
besonderen Kommission. 2, Aufstellung einer Check-List für Europa. 3, Erarbeitung von genauen Arbeits- 
anweisungen und Arbeitsunterlagen (Kartenmaterial etc.). 4, Aufstellung einer Liste der Arten, deren 
Kartierung vordringlich erscheint (z.b., Vertigo moulinsiana, Margaritifera margar iti fera, Candidula 
unifasciata). Hierbei sollten vor allem Arten Berücksichtigung finden, deren Biotope gegenwärtig und in 
Zukunft besonders gefährdet sind. 



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MALACOLOGIA, 1973, 14: 415-418 

PROC. FOURTH EUROP. MALAC. CONOR. 
SUR QUELQUES PISIDIUM HA UT -ALPINS 
*Adrien Jayet 
Laboratoire de Paléontologie, Université de Genève, Suisse 

La faune des Pisidium alpins est très mal connue; les observations demeurent 
sporadiques, elles demandent en effet de forts déplacements à des altitudes variées 
et sur des distances considérables. Ces faits expliquent dans une certaine mesure 
le manque d'intérêt des^ malacologistes pour ce groupe de Lamellibranches; nos 
propres observations ont été faites au cours d'excursions géologiques. 

Les matériaux que nous utilisons ont été récoltés par Jules Favre, par ses collabor- 
ateurs, enfin par nous même; ils sont déposés au Museum d'histoire naturelle de 
Genève, les déterminations sont celles de J. Favre. 

Les notes qui suivent sont, par la force des choses, très incomplètes. En les 
publiant nous avons pour but essentiel d'attirer l'attention sur le groupe des Pisidium, 
leur étude systématique apporte aussi bien dans le domaine de la Biologie que dans 
celui de la Paléontologie une multitude de précieux renseignements. 

La zone alpine qui nous retiendra est comprise entre 2000 et 2800 m. La carac- 
téristique en est que les nappes d'eau sont recouvertes de glace pendant une grande 
partie de l'année, très spécialement la sous-zone de 2500-2800 m. Cette dernière 
est située au-dessus de la limite des arbres tandis que la sous-zone 2000-2500 m est 
presque toujours dans la région des forêts. Au point de vue géographique les localités 
indiquées se rapportent à la zone pennique du Valais, aux Grisons et à la Haute-Savoie. 

Les nappes d'eau fréquentées par les Pisidium sont des lacs, souvent de dimen- 
sions très réduites, des marais, des ruisseaux de caractère torrentiel, enfin des 
mares artificielles et des fossés. Jusqu'à présent aucune recherche n'a été faite, à 
ma connaissance, dans la zone profonde des lacs alpins. Nos documents proviennent 
donc seulement de la zone littorale ou encore des eaux peu profondes des cours d'eau. 

Dans la zone pennique du Valais, les sédiments, dérivant de roches métamorphiques, 
sont des sables, ils sont peu favorables et ce n'est que dans les plages limoneuses 
et terreuses, au voisinage de la végétation que l'on peut trouver des Pisidium. 

Pour l'instant nos connaissances se bornent à trois espèces, soit: P. casertanum 
Poli, P. hibernicum Westerlund,P. personatumMalm. Ce nombre très faible d'espèces 
s'augmentera certainement par la suite comme semble le prouver la découverte de 
P. lapponicum Clessin en Engadine, de P. nitidum Jenyns dans le lac Champex, etc. 

Répartition en verticale. Des 17 localités d'où proviennent les Pisidium haut-alpins 
de la collection J. Favre, 8 sont comprises entre 2000-2500 m et 9 au delà soit de 
2500-2800 m. Nous indiquons ci-dessous et pour chaque espèce ces localités par 
ordre d'altitude croissant. 

Pisidium casertanum Poli 

Amont de Mauvoisin 2002 m (Val de Bagnes, Valais), Champlong 2200 m (V. d'Entre- 
mont, Valais); Valsorey 2350 m (V. d'Entremont, Valais); Val Scarl 2350-2400 m 
(Grisons); Chanrion 2470 m (V. de Bagnes, Valais); Stellisee 2453 m (région de 
Zermatt, Valais); Combe des Planards 2550 m V. d'Entremont, Valais; Schwartzsee 
2556 m (r. de Zermatt, Valais); Ofenpass 2600 m (Grisons); Riffelsee 2780 m (R. de 
Zermatt, Valais). 

Pisidium hibernicum Westerlund 

Col. d'Anterne 2000 m (Haute-Savoie); Valsorey 2350 m (V. d'Entremont, Valais); 



c Deceased 

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416 PROC. FOURTH EUROP. MALAC. CONGR. 

Schwartzsee 2556 m (r. de Zermatt, Valais); Forclettaz 2600 m (Val d'Annivers, 
Valais). 

Pisidium personatum Malm 

Les Vergys 2000 m (Haute-Savoie); Stellisee 2543 m (r. de Zermatt, Valais); fond 
de la combe des Planards 2800 m (V. d'Entremont, Valais). 

Morphologie 

La coquille des Pisidium haut-alpins est le seul élément dont nous avons eu à nous 
occuper, elle est très semblable à celle des espèces de la plaine. Il faut toutefois 
signaler quelques différences entre les unes et les autres. Dans la plaine les différ- 
entes formes ou variétés se groupent autour de trois principaux modes de variation: 
a) formes typiques, b) formes pondêreuses, c) formes rabougries. 

Chez les Pisidium haut-alpins nous n'avons pas constaté de formes pondêreuses, 
celles-ci exigent des températures régulièrement élevées et une forte teneur de l'eau 
en carbonate de calcium. Nous n'avons pas non plus constaté de formes très ra- 
bougries, ce qui signifie que les Pisidium se situent au voisinage du type. 

Toutefois il se dégage d'un examen détaillé un certain nombre de traits communs 
à tous les Pisidium de haute altitude, traits qui les distinguent de ceux de la plaine. 
Notre attention avait été attirée par J. Favre sur un trait caractéristique de P. 
hibernicum haut-alpin, il avait appelé cette forme P. hibernicum var. giganteum mais 
sans en donner une description, nous compléterons ce point ci-dessous. A la suite de 
la remarque de J. Favre nous nous sommes demandé si les deux autres espèces ne 
présenteraient pas aussi des formes plus grandes que le type et tel est bien le cas. 

P. casertanum Poli 

Les individus adultes du Valsorey mesurent 4 à 4, 8 mm avec une moyenne de 4,3 mm. 
Par contre les formes de la plaine mesurent 3,5 à 4 mm pour les formes typiques. 
Il semble donc bien que les P. casertanum alpins soient plus grands que leurs con- 
génères de la plaine. 

P. hibernicum Westerlund var. giganteum J. Favre 

Les dimensions des adultes de Valsorey (2350 m) varient de 3,2 à 3,8 mm. Par 
contre le type de la plaine mesure de 2,5 à 3 mm, ce qui justifie bien l'appellation de 
J. Favre. Nous ajoutons la diagnose succinte suivante: test mince, stries d'accroisse- 
ment déjà visibles sur la protodyssoconque, forme un peu moins équilatérale que le 
type, par conséquent un peu plus allongée dans le sens transversal. 

P. personatum Malm 

D'après J. Favre les individus que nous avions récoltés à la combe des Planards 
à 2800 m correspondent à une "curieuse forme à galbe ovale". Les dimensions varient 
de 3,5 à 4 mm avec une moyenne de 3,7 mm. Là encore la forme alpine diffère du 
type de plaine qui mesure 3 à 3,6 mm. 

La tendance des Pisidium haut-alpins à une augmentation de la taille est donc 
générale, elle entraîne de part et d'autre du crochet une certaine inégalité, la partie 
antérieure étant plus développée que la postérieure; en d'autres termes elle devient 
moins équilatérale. 

Il s'agit maintenant d'examiner un problème important. A considérer le climat 
alpin on doit penser qu'il se rapproche plus que d'autres de celui qui devait régner 
à la fin de l'extension glaciaire (fin du Wurm, période dite Dryas des palynologues). 
Lors de cette période les conditions climatiques sont rudes, elles se traduisent pour 
les Pisidium par une modification de la croissance de la coquille, Celle-ci se fait 
par à coups, ce sont des arrêts de croissance ou d'une façon plus simple des irrégu- 
larités de croissance. Elles déterminent un profil irrégulier en zig-zag alors que ce 



JAYET 417 

dernier est régulièrement convexe chez les formes normales. Dans la plaine, les 
espèces atteintes d'irrégularités de croissance sont celles du Pleistocene récent, on 
les considère souvent comme des espèces reliques. Ce sont P. lapponicum dessin 
(ou P. obtusale С Pfeiffer var. lapponicum. Clessin), P. hibernicum Westerlund, P. 
li lije borgt Clessin. 

Des trois espèces haut-alpines, c'est donc P. hibernicum qui devrait présenter le 
phénomène des arrêts de croissance, or nous constatons qu'il n'en est rien ou plus 
exactement que ces irrégularités sont si faibles qu'elles se fondent dans celles des 
stries d'accroissement. 

Un autre caractère est celui de la charnière. Celle des Pisidium haut-alpins est 
toujours mince, les dents cardinales et latérales sont développées normalement mais 
sans exagération, leur allure se rapproche un peu de celle des formes rabougries de 
la plaine. 

En résumé, les formes de haute altitude se distinguent de celles de la plaine par 
leurs dimensions un peu plus fortes, leur coquille et leur charnière minces. Elles 
sont d'allure très uniformes et ne présentent pas la gamme de variations que l'on 
observe ailleurs, elles témoignent donc d'unbiotope particulièrement homogène. 

Age de la pénétration des Pisidium dans la région alpine 

Il est difficile de connaître exactement les phases du peuplement actuel des Alpes, 
qu'il s'agisse de la faune ou de la flore. On peut toutefois supposer qu'il s'est effec- 
tué au cours du retrait glaciaire würmien. La géologie indique pour le glacier du 
Rhône un front glaciaire en amont de Villeneuve qui pourrait correspondre à la période 
magdalénienne. Ce serait alors au cours de la période suivante, au Mésolithique que 
se situeraient les principales étapes du retrait glaciaire dans la vallée du Rhône valai- 
san et ce serait aussi l'âge du peuplement des Alpes par la végétation et par les faunes. 

Une constatation vient à l'appui de cette manière de voir. Dans la plaine les 
formes reliques disparaissent à la fin du Pleistocene avant le Mésolithique quoique 
certaines se soient maintenues dans des milieux particulièrement favorables tels 
que le Léman. La raison de la pauvreté en Pisidium des régions haut -alpines pourrait 
bien s'expliquer par le fait que le retrait glaciaire a été particulièrement tardif dans 
les hautes régions. 

Un autre fait vient appuyer cette opinion; à l'heure actuelle c'est le P. casertanum 
que pénètre partout dans les nappes d'eau crées artificiellement, fossés, canaux, 
petits lacs artificiels. Le même fait s'observe dans des régions d'altitude moindre, 
Jura, Salève, etc. D'après J. Favre (1927) ce Pisidium est rare dans les dépôts post- 
glaciaires anciens, c'est donc pour les Alpes une espèce d'introduction relativement 
récente mais qui manifeste un grand pouvoir d'extension, la liste des localités qui le 
contiennent en fait foi; il est encore possible que la période actuelle de réchauffement 
lui soit particulièrement favorable. 

CONCLUSIONS 

Les espèces de Pisidium haut-alpins sont peu nombreuses, les observations ne 
donnent à ce jour que trois espèces soit P. casertanum, P. hibernicum, P. personatum, 
mais les recherches futures augmenteront certainement ce nombre. 

Tous les milieux aquatiques de la zone 2000-2800 m peuvent abriter des Pisidium, 
toutefois les milieux sableux leur sont contraires. 

Au point de vue morphologique, les Pisidium haut-alpins présentent des formes un 
peu plus grandes que celles de la plaine, la variété giganteum de P. hibernicum en 
est un bon exemple. La coquille est mince, la charnière étroite, avec les dents 
cardinales et latérales elle rappelle un peu celle des formes rabougries de la plaine. 



418 PROC. FOURTH EUROP. MALAC. CONGR. 

Il n'y a pas ou très peu d'irrégularités de croissance. 

Le peuplement des Alpes en Pisidium s'est probablement poursuivi pendant l'extrême 
fin du Pleistocene, au cours du Mésolithique et des périodes plus récentes. Le P. 
casertanum est le plus répandu et son extension se poursuit actuellement tandis que 
P. hibernicum fait figure d'espèce relique. Le P. personatum reste encore le plus 
mal connu. 

Il faut insister sur l'intérêt que présenteraient des recherches systématiquement 
poursuivies, les quelques observations exposées ci-dessus doivent être considérées 
comme un aperçu très incomplet et en quelque sorte préliminaire. 

BIBLIOGRAPHIE 

CHAIX, L., 1970, Essai de corrélation entre palynologie et malacologie dans les 

sédiments post-glaciaires du sud du Bassin lémanique. C. r. Séances Soc. Phys. 

Hist, natur. Genève, 5,1. 
FAVRE, J., 1927, Les mollusques post-glaciaires et actuels du Bassin de Genève. 

Mém. Soc. Phys. Hist, natur. Genève, 40,3. 
FAVRE, J., 1941, Les Pisidiums du Canton de Neuchâtel. Bull. Soc. neuchâteloise 

Sei. natur., 66. 
FAVRE, J. & JAYET, A., 1938, Deux gisements post-glaciaires anciens à Pisidium 

vincentianum et Pisidium lapponicum aux environs de Genève. Ecl. geol. Helvetiae, 

31,2. 
FAVRE, J. & JAYET, A., 1950, Un nouveau gisement post-glaciaire ancien à Pisidium 

vincentianum et Pisidium lapponicum aux environs de Genève. J. Conchyliol., 90. 
JAYET, A., 1969, Les sédiments de la Grande-Buge prés de Baulmes (Vaud, Suisse) 

essai d'une corrélation entre malacologie et palynologie. C. r. Séances Soc. Phys. 

Hist, natur. Genève, 4,1. 



MALACOLOGIA, 1973, 14: 419-425 

PROC. FOURTH EUROP. MA LAC. CONGR. 

DISTRIBUTION PATTERNS OF THE GENUS GULELLA (GASTROPODA PULMONA TA: 
STREPTAXIDAE) IN SOUTHERN AFRICA 

A. C. van Bruggen 

Department of Systematic Zoology of the University 
c/o Rijksmuseum van Natuurlijke Historie, Leiden, Holland 

The genus Gulella L. Pfeiffer 1856 consists of small (length of shell 1.5-22 mm) 
carnivorous snails which as a rule belong to the cryptofauna of various types of 
forest and savanna. The genus is distributed over much of sub -Saharan Africa and 
adjacent islands except in really arid areas; however, some species have even been 
obtained in Somalia and South West Africa. Outside Africa the genus is sparsely 
represented on the Comoro Is., Aldabra Is., Seychelles Is., Mauritius and Madagascar. 
The shells are usually pupiform and as a rule supply stable and reliable characters, 
mainly in the arrangement and number of denticles and other processes in the aperture, 
and in the shape and costulation of the shell. Radula and genitalia so far have con- 
tributed little of real taxonomic value. The genus is very diverse and hundreds of 
species are known from the African continent. Connolly's monograph (1939) enumerates 
123 species south of the Zambezi and Cunene Rivers which number is approximately 
correct because of additional species and (expected) synonymies. The synonymy ratio 
(cf. Boss, 1971: 83, 86) appears to be low and stands at 1.4/1, but may increase to 
1.5/1. The present author has undertaken a revision of these species and the results 
given below are in the nature of a summary interim report on distribution data. 

The distribution of the genus in Southern Africa is shown in Fig. 1. Only marginal 
localities marking the western limits have been indicated. The main range of Gulella 
in the southern parts of Africa lies east of the line Swell endam-Somerset East-Cradock- 
Middelburg (C.P.)-Bloemfontein-Kroonstad-Potchefstroom-Rustenburg-Mount Moha- 
paam^-Blouberg-Matopos-Khami-Victoria Falls. Outside this area we have only 3 
records for 1 species from South West Africa (Otavi Highlands, Omaruru District, 
Diab River) and 1 for a closely allied form from the dry parts of the north-central 
Cape Province (Prieska). South West Africa is malacologically comparatively well- 
known so that Gulella may occur here only in scattered localities. Lack of records 
west of the line on the map is probably due to the lack of suitable habitats and perhaps 
in addition to a dearth of collectors. Much of Botswana (Bechuanaland), South West 
Africa and the northwestern districts of the Cape Province are obviously too arid for 
Gulella, while on the other hand species of the genus may be expected to occur in 
certain malacologically poorly explored regions of Botswana (e.g., Ngamiland) and 
South West Africa (e.g., Caprivi Strip). Most of the area inhabited by Gulella in 
Southern Africa has a rainfall in excess of 20 inches (= 500 mm) per annum, although 
obviously a lower rainfall definitely does not prevent a few species from surviving in 
sheltered localities (e.g., Kruger National Park). Attention is drawn to the course 
of the line in Fig. 1, which line only pretends to be an approximation as regards 
the local western boundary of the genus. In the southern part of the range the real 
boundary is probably the watershed of the Drakensberg range separating the fairly 



Not in Botswana (Bechuanaland), but in the Transvaal {fide Van Bruggen, 1969: 28); Gulella 
miniata (Krauss) therefore has to be expunged from the Botswana list (Van Bruggen, 1966a: 110), 
so that there are at present as yet no records for the genus from that country. 

(419) 



420 



PROC. FOURTH EUROP. MALAC. CONGR. 





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FIG. 1. Map of Southern Africa showing the western limits of the genus Gulella (heavy broken 
line); note 4 isolated localities west of the line. Contour line of 1000 m, isohyet of 20 inches = 
500 mm mean annual rainfall, and mean 18°с July isotherm also indicated. H. Heijn del. 



VAN BRUGGEN 421 

humid eastern coastal area and the dry Karoo northwest of the mountains, while in 
the eastern Transvaal the boundary may follow the various isohyets very closely. 
Actually the Limpopo River valley on the borders of the Transvaal and Rhodesia forms 
an arid corridor, thereby interrupting the distribution of various fauna elements on 
both sides of the river. Consequently the line between the Blouberg and the Matopos 
should follow part of the 20 inches isohyet eastward around the Limpopo River through 
Mozambique rather than connect the above 2 localities with an almost straight line. 

Scattered occurrence west of the line may be explained by a reduction in rainfall 
since the last pluvial or hypothermal (cool-humid) period (cf. Van Bruggen, 1969: 75). 
Therefore one might consider occurrence outside the main range to be of a relict 
nature. Indeed, the 1 species from South West Africa, the status of which is as yet 
uncertain (for the time being recorded s.n. Gulella caryatis diabensis Connolly), is 
probably closely allied to a fairly widely distributed species which is adapted to 
comparatively arid conditions as shown by its distribution along the western limits 
of the genus in South Africa. Incidentally, this is the species recorded from Prieska: 
G. caryatis (Melvill & Ponsonby). 

East of the line there is a fair to large amount of rainfall and various types of 
vegetation exist suitable to species of Gulella. The genus is of tropical origin and 
there is a rapid decline in number of species from north to south in a markedly 
narrowing belt along the east coast east of the main watershed in the form of the 
Drakensberg range. Approximately 50 species occur in the Cape Province, many of 
which only penetrate as far south as the northeastern part of the province (Pondoland). 
The southernmost record for the genus is at about 34°S (Swellendam). 

Although it may seem somewhat dangerous to draw up distribution patterns of small 
snails in Southern Africa, one should realize that this part of Africa is comparatively 
well-collected in this respect; hundreds of specimens in a very large number of 
samples, mainly belonging to the Natal Museum (Pietermaritzburg, South Africa), 
warrant at least careful consideration. 

Only 5 species or 4% of the total are not endemic to the Southern African subregion, 
i.e., are also found north of the Zambezi River. Gulella rhodesiana (Connolly) is only 
found in the northern Transvaal and on both banks of the Zambezi at the Victoria Falls. 
The other 4 are among the few really widely distributed species, viz., G. gouldi 
(Pfeiffer) from the eastern Cape Province (Bathurst: 33°30'S 26° 50' E) to Zululand 
(Ndumu Game Reserve, Ndumu hamlet: 27°56' S 32°16'E), and the Usambaras (about 
5° 09' S 38°36*E) in continental Tanzania; G. planidens (Von Martens) from the Rhodesia- 
Mozambique eastern escarpment (Lundi and Vila Pery respectively) to continental 
Tanzania, Uganda and Congo-Kinshasa, and westward to Senegal (probably the most 
widely distributed species in the genus if not in the family 2 ); G. sexdentata (Von Mar- 
tens) from Zululand to Tanzania (including Zanzibar); G. vicina (Smith) from the 
Rhodesian eastern escarpment (Mount Selinda) to Kenya, Uganda and Congo-Kinshasa. 

Three of these (if not all) are to be divided into well-marked subspecies, Gulella 
gouldi even into geographically widely separated forms (2 in Southern Africa, 1 in 
Tanzania), which fact may also be due to changes in the climate of Africa. Generally 
variation on a subspecific level is uncommon among Southern African Gulella, only 8 
such species at present being known: the 4 above-mentioned non-endemic and widely 
distributed species in addition to G. caryatis (see above), G. crassidens (Pfeiffer), G. 
darglensis (Melvill & Ponsonby) and G. elliptica (Melvill & Ponsonby). A few more such 
species may be discovered in the course of current investigations. 



2 The greatest distance over which the range of Gulella planidens extends is approximately 6000 
km or 3800 miles; compare G. vicina with about 2500 km or 1500 miles. 



422 PROC. FOURTH EUROP. MALAC. CONGR. 

All above non-endemics, except for Gulella gouldi, belong to the tropical element 
in Southern Africa, i.e., are unknown south of the Limpopo and Tugela Rivers. Inci- 
dentally, the distribution pattern of G. gouldi in South Africa is a typical "collector's 
pattern" in Natal; it closely follows the coastal road where there is a string of sea- 
side resorts from the southern borders of the province to the banks of the Tugela 
River, while from Durban inland it follows the main road through Pietermaritzburg to 
Johannesburg. Nevertheless it somehow conveys a picture of the distribution of the 
species and allows for more or less reliable extrapolation as to its occurrence outside 
the main roads. One may, for example, expect it to occur throughout much of the 
lower parts of Natal and Zululand, which may also apply to its range in the eastern 
Cape Province (cf. Van Bruggen, 1969: 44, fig. 15). 

Roughly 20% of the species are at present only known from their type localities, 
which may be due to poor collecting but also to endemism, particularly with refer- 
ence to physiographical conditions. Many endemic species do not conform to a geo- 
graphical pattern and may indeed be poorly collected taxa; on the other hand certain 
patterns are quite obvious and are moreover confirmed by similar patterns in other 
groups of animals. The broken Drakensberg range in the Transvaal, Rhodesia and 
Mozambique shows some striking patterns as far as Gulella is concerned. Four 
separate regions are isolated by low-lying and much drier country: south and north 
of the Olifants River, the Zoutpansberg area and the Rhodesia-Mozambique eastern 
escarpment, each with 2-5 endemics in addition to 0-5 other species. The major 
part of these regions is over 1000 m or 3000 ft. Thus a fair number of species 
with numberous processes and intricate patterns in the aperture and with a very limited 
distribution (frequently at higher altitudes) probably are products of geographical 
isolation. An example of this isG. ymeBurnup, a minute costulate species known only 
from about 2500 to 8000 ft. in parts of the Drakensberg range in Natal and the Trans- 
vaal. 

The relationships of such endemic species are sometimes complicated and therefore 
not easily explained. Some species showing unique dental patterns are obviously so 
highly specialized that it is clear that these species are taxonomically more or less 
isolated and speculation as to their ancestry seems premature. Others clearly show 
relationships, such as those of the widely distributed and intricately interrelated 
Gulella infans (Craven) group, which probably has various derivatives in the upland 
forests. 

There is also possibly a relationship between Gulella crassilabris (Craven), G. 
distincta (Melvill & Ponsonby) and G. sibasana Connolly (Fig. 2). These species are 
largely allopatric, except for the 1st 2 which occur side by side in the central districts 
of the Kruger National Park (Van Bruggen, 1966b: 385, fig. 64), thereby proving their 
separate identities. It is possible that these species are derived from a common 
ancestor, although it is a moot point whether the forest dweller G. sibasana is closer 
to the ancestor than the 2 inhabitants of the much drier and somewhat lower areas. 
In view of the fact that Southern Africa now experiences an interpluvial (warm-dry) 
period (Van Bruggen, 1969: 75) it may be more plausible to consider G. crassilabris 
and G. distincta offshoots of G. sibasana rather than otherwise. In this case the moun- 
tain forest environment has certainly a longer and more continuous history than the 
much drier mid- and lowlands of the Transvaal, or, conversely, when the forest 
contracted with the onset of another dry period G. crassilabris and G. distincta must 
have adapted themselves in geographically separated areas to a drier climate and 
resultant vegetation, which allowed them to stay where they were and possibly even to 
increase their range, thereby coming in contact with each other in the eastern Trans- 
vaal (Kruger National Park). In this context we may perhaps consider the G. sibasana 
complex a superspecies. 



VAN BRUGGEN 



423 



BOTSWANA 



of? 



MOZAMBIQUE 



TRANSVAAL 



*Vi 




CAPE PROVINCE 



INDIAN OCEAN 



EL 



PL- 



■ G sibasana 
• G crassilabris 
▲ G. distincta 



1000 m contour 
1500 m contour 
2000 m contour 



26° 



28° 



32» 



FIG. 2. Distribution of Gulella sibasana Conn. , G. crassilabris (Crvn) and G. distincta (M. & 
P.). Abbreviations of towns: B, Bloemfontein; D, Durban; EL, East London; J, Johannesburg; 
LM, Lourenço Marques; P, Pretoria; PE, Port Elizabeth. H. Heijndel. 



It is interesting to check on some general principles of evolutionary biology as 
regards the Southern African species of Gulella. Important characters are apertural 
dentition and costulation of the shell. Many species are clearly marked by showing 
more or less prominent ribbing, others being smooth or almost so. Some costulate 
species, however, have populations with weakly costulate to even practically smooth 
shells. Here the question arises whether species with smooth shells belong to more 
primitive stock than species with costulate shells. Primitive streptaxids probably 
had smooth shells with little apertural dentition (see, e.g., Van Bruggen, 1967). 
Some of the widely distributed species, such as the above-mentioned G. planidens and 
G. sexdentata, indeed have smooth shells, while on the other hand G. planti (Pfeiffer) 
(smooth) and G. zuluensis Connolly (faintly costulate) both have a very limited distri- 



424 PROC. FOURTH EUROP. MALAC. CONGR. 

bution. These 2 species are also comparatively large and have only 2-3 processes in 
the aperture. This may lead to the conclusion that both are possibly derived taxa 
having had as yet no time to expand their range or perhaps are adapted to a unique 
situation. A 3rd possibility is that they have ceased to exist elsewhere. G. planti is 
Southern Africa's largest species (shell length up to 21.5 mm). Generally one finds 
that species with large shells (length 12 mm and over) have a restricted distribution, 
which also applies to other parts of Africa. Incidentally, the majority of these large 
species seems to dwell in the uplands of Africa. 

The Gulella infans group consists of species with small shells and few processes 
in the aperture; both costulate and smooth shells are represented here, even sometimes 
within the same species. The wide distribution of the G. infans group correlated with 
limited dentition, frequently smooth shell, and small size may indicate that this group 
represents a somewhat primitive or ancient element in the genus. Convergent evolu- 
tion, leading to almost identical types of shell, cannot be excluded here. Some West 
African and a Madagascar species are conchologically close to the G. infans group but 
may be only distantly related. 

Rensch (1932) has shown that sculpture in general is more marked in dry and warm 
than in cooler and more humid areas. In the case of Gulella this may also be a com- 
plicating factor. The one form in arid South West Africa is decidedly more costulate 
than its nearest allies in less arid environments (see above). On the other hand many 
forest dwelling endemics are markedly costulate and probably are derived from 
smooth species, which only shows that the picture is really much more complicated. 

Finally, is there perhaps a correlation between the dental pattern in the aperture 
and the costulation of the shell? As a working hypothesis one may predict a positive 
correlation between a smooth shell and a limited apertural dentition, or, conversely, 
a costulate shell with an intricate pattern of processes in the aperture. Both types 
are difficult to delimit. A preliminary survey of the Southern African species revealed 
that about 2/3 of the species do indeed show a positive correlation between dental 
pattern and sculpture of the whorls. However, all in all this is perhaps not quite 
sufficient to prove the point in question. 

REFERENCES 

BOSS, K. J., 1971, Critical estimate of the number of Recent Mollusca. Осе. Paps. 

Molls., 3: 81-135. 
BRUGGEN, A. C. van, 1966a, Notes on non-marine molluscs from Mozambique and 

Bechuanaland, with a checklist of Bechuanaland species. Ann. Transv. Mus., 25: 

99-111. 
BRUGGEN, A. С van, 1966b, The terrestrial Mollusca of the Kruger National Park: 

a contribution to the malacology of the Eastern Transvaal. Ann. Natal Mus., 18: 

315-399. 
BRUGGEN, A. С van, 1967, An introduction to the pulmonate family Streptaxidae. 

J. Conchol., 26: 181-188. 
BRUGGEN, A. С van, 1969, Studies on the land molluscs of Zululand with notes on the 

distribution of land molluscs in Southern Africa. Zool. Verh. Leiden, 103: 1-116. 
CONNOLLY, M., 1939, A monographic survey of South African non-marine Mollusca. 

Ann. S. Afr. Mus., 33: 1-660. 
RENSCH, В., 1932, Ueber die Abhängigkeit der Grösse, des relativen Gewichtes und 

der Oberflächenstruktur der Landschneckenschalen von den Umweltsfaktoren 

(Oekologische Molluskenstudien I). Z. Morph. Oekol. Tiere, 25: 757-807. 



VAN BRUGGEN 425 

RESUME 

MODELES DE DISTRIBUTION DU GENRE GULELLA (GASTROPODA PULMONATA: 
STREPTAXIDAE) EN AFRIQUE AUSTRALE 

Le genre Gulella est très répandu dans le sud-est de l'Afrique australe (environ 
125 espèces). Sur la carte (Fig. 1) la ligne en traits interrompus indique la limite 
occidentale du genre; à l'ouest de cette ligne on ne connait que quatre localités. 
Seulement quatre espèces (G. gouldi, G. planidens, G. sexdentata et G. vicina) se 
trouvent aussi au nord du Zambèze. Les autres sont endémiques et souvent très 
localisées. G. sibasana, G. crassilabris et G. distincta sont peut-être originaires d'un 
ancêtre commun (Fig. 2). Le groupe de G. infans comprend des espèces de petite 
taille, avec une ouverture à peu de dents; ce groupe est très répandu de sorte qu'il 
peut être relativement primitif ou ancien. Les coquilles d'environ deux tiers des 
espèces de l'Afrique australe montrent une corrélation positive entre le nombre (et 
le développement) des dents à l'ouverture et la présence ou l'absence d'une sculpture 
sur les tours (ornementation sous forme de côtes ou de stries). 



MALACOLOGIA, 1973, 14: 426 

PROC. FOURTH EUROP. MALAC. CONGR. 
DIE FORMEN VON ABIDA SÉCALE (DRAPARNAUD) IN DEN ÖSTLICHEN PYRENÄEN 

E. Gittenberger 
Rijksmuseum van Natuurlijke Historie, Leiden, Netherlands 
ZUSAMMENFASSUNG 1 

Die Gehäuse von Abida sécale (Draparnaud) variieren im grössten Teil des Verbreitungsgebietes der Art, 
das von Spanien ostwärts bis in Ungarn reicht, fast nur in den Massen und im Habitus. Die Gestaltung der 
Mündung und der Mündungsarmatur ist dabei auffallend konstant. 

Im östlichen Teil der Pyrenäen hingegen ist eine erstaunlich grosse, geographisch bedingte, Variabilität 
vorhanden, die sich nicht auf Habitus und Masse beschränkt. Nur durch ein paralleles Studium von Morpho- 
logie und geographischer Verbreitung der verschiedenen ^Wda-Populationen werden die Zusammenhänge 
deutlich. 

Es ergibt sich, dass einige stark differenzierte Formen, die immer als Arten betrachtet wurden, als 
Unterarten zu Abida sécale gestellt werden müssen auf Grund der genetischen Zusammenhänge, die sich 
in Vorkommen und Verbreitung von Uebergangsformen zeigen. Aus gleichen Gründen müssen zwei Abida- 
Formen, die ohne Uebergänge zusammenleben zu A. sécale gestellt werden. Sie hängen indirekt, durch 
weitere Formen, zusammen. 

Die Art wird als eine genetische Entität gesehen. Im Rahmen einer Behandlung der taxonomischen 
Gliederung einiger Delima-Formen bemerkt Nordsieck (1969: 274), dass ". . . bei vielen Arten offenbar 
die Fortpflanzungsisolation noch unvollständig ist, also die morphologische Differenzierung schneller 
vonstatten ging als der Erwerb isolierender Mechanismen" und spricht etwas weiter von Formen, die 
"wegen der morphologischen Differenzierung" als verschiedene Arten aufzufassen sind. Eine solche, 
morphologische Begründung des Artbegriffs wird abgelehnt. 

SCHRIFTTUM 

NORDSIECK, H., 1969, Zur Anatomie und Systematik der Clausilien, VI. Genitalsystem und Systematik 
der Clausiliidae, besonders der Unterfamilie Alopiinae. Arch. Molluskenk., 99(5/6): 247-265. 



1 In extenso in: Gittenberger, E., 1973, Beiträge zur Kenntnis der Pupillacea, III. Chondrininae. Zool. Verh., 
Leiden, 127. 



MALACOLOGIA, 1973, 14: 426 

PROC. FOURTH EUROP. MALAC. CONGR. » 

ZOOGEOGRAPHY OF THE PLEUROCERINE FRESHWATER SNAILS 

Joseph P. E. Morrison 

U. S. National Museum of Natural History, Washington, D. C, U.S.A. 

ABSTRACT 

The Amphimelaniinae of Europe, Melanatriinae of Africa, Paludominae of Asia, and the Pleurocerinae of 
North and Central America are confluent as 1 subfamily, with identical female egg-laying structures. The 
detailed pattern of egg-laying and the egg-mass is still considered a generic character. The Pleurocerinae 
are thus primarily Holarctic. 

The Recent pleurocerids of Europe (from the Danube System) are now incorrectly called Amphimelania. 
The name Holandriana Bourguignat May 1884, with the type species Melania holandri C. Pfeiffer 1828, 
precedes Amphimelania Fischer 1885 and should be used. 

The closely related Family Melanopsidae includes Melanopsis of Europe, North Africa to Iraq and of 
New Caledonia. Zemelanopsis of New Caledonia and New Zealand re-covers the apical whorls with an added 
covering of periostracum (and shell layers) effectively hiding the 4 first whorls of the shell. 

The Melanopsidae of the Danube and Dniester River Systems are now incorrectly called Fagotia. The 
names of Bourguignat 1877, including Esperiana (type esperi), were reported by Bourguignat (May, 1884, 
p 3), before he placed the same group 1st under Fagotia on p 30. As the earliest name, Esperiana must be 
used for this genus. Microcolpia Bourguignat 1884, p 49, will remain as a subgenus for Esperiana 
(Microcolpia) acicularis Ferussac. 



(426) 



MALACOLOGIA, 1973, 14: 427 

PROC. FOURTH EUROP. MALAC. CONGR. 

A PROGNOSIS IN THE SPREAD OF THE GIANT AFRICAN SNAIL TO CONTINENTAL UNITED STATES 

Albert Raymond Mead 

University of Arizona, Tucson, Arizona, U.S.A. 

ABSTRACT 

The giant African snail, Achatina fúlica, has been on the move from its east African home for over 150 
years. That it had not become established in any continental site in the Western Hemisphere until recently 
is virtually a biological enigma. Its 1st point of establishment in the Western Hemisphere was in the 
Hawaiian Islands in 1936. In spite of the most intensive control and quarantine measures ever initiated 
against this pest, it is still spreading. It was not until 1969 that it was found thoroughly ensconced in 
North Miami and Hollywood, Florida. Since then, over 17,000 specimens have been collected and destroyed 
at an expense of over $80,000. The population is being contained but currently is holding at the "irreducible 
minimum." Every feasible control measure except biological control has been initiated and carried through 
by qualified personnel on a rigid program. This snail pest never has been eradicated in any place in the 
world where it has become established as a population. There is now the best chance that man has ever 
had successfully to contain and eventually eradicate this largest major land snail pest. The next 12-24 
months will doubtless prove decisive. If the present program fails, it is predicted that A. fúlica will 
eventually spread north to the Carolinas and west, through the Gulf states, spottedly through the South- 
western "desert" states, and into southern California; from these areas it easily could spread to the 
Caribbean islands, Mexico, Central and South America. The phenomenon of natural population decline, 
manifested in virtually all of the older populations that have been examined, holds the key to eventual 
practicable control. 



(427) 



MALACOLOGIA, 1973, 14: 429-430 

PROC. FOURTH EUROP. MALAC. CONGR. 

MOLLUSQUES DES ILES TUBUAI (AUSTRALES, POLYNESIE) 
COMPARAISONS AVEC LES ILES DE LA SOCIETE ET DES TUAMOTU 

Bernard Salvat 

Laboratoire Biologie Marine et Malacologie 
Ecole Pratique des Hautes Etudes, Muséum Paris, France^- 



L'Archipel des îles Tubuai, ou Australes, entre 144 et 154° de longitude Ouest 
comprend sept îles disposées selon un axe Nord-Ouest - Sud-Est traversant le tropique 
du Capricorne. Entre l'île la plus occidentale, Maria, et la plus orientale, l'îlot de 
Bass, s'échelonnent les cinq principales îles de l'Archipel: Rimatara, Rurutu, Tubuai, 
Raevavae et Rapa. Cet ensemble se situe au Sud-Est et au Sud des Archipels de la 
Société (îles hautes volcaniques dont Tahiti et Bora-Bora), des Tuamotu (îles basses 
ou atolls dont Rangiroa, Raroia, Mururoa) et des Gambiers (îles hautes dont Mangareva, 
Aukena). 

Les deux principales îles méridionales de l'Archipel des Tubuai, Raevavae et Rapa, 
sont intéressantes du point du vue écologique et biogéographique car l'une présente un 
climat tropical alors que l'autre possède un climat tempéré. Ces deux îles ont été 
l'objet, en avril-mai 1968, de prospections malacologiques 2 . 

Raevavae, île volcanique de 9 km de longueur, possède des récifs frangeants et un 
lagon entouré par un récif barrière presque continu. Cette île est située à la même 
latitude (23° Sud) que les Gambiers. Comparativement à la faune de ces dernières 
îles, la faune du lagon de Raevavae est bien plus pauvre en nombre d'espèces alors 
que la faune des récifs extérieurs est analogue, peu de différence pouvant être notée. 
Des études précédentes (Salvat 1970a, b) ont montré que les Mollusques caractéris- 
tiques des récifs extérieurs, supprimer du récif barrière des îles volcaniques 
Gambiers (23° latitude Sud) comme de la bordure océanique de l'atoll de Fangataufa 
(22° de latitude Sud) dans les Tuamotu, sont les mêmes: Turbo setosus (Gmelin, 1791), 
Nerita plicata Linné, 1758, Littorina coccínea (Gmelin, 1791), Vermetus maximus Sow., 
1825, Drupa gros sularia (Röding, 1798), D. hórrida (Lamarck, 1816), D. morum 
Rô'ding, 1798, D. ricinus (Linné, 1758), Morula granulata (Duelos, 1832), Strigatella 
litterata (Lamarck, 1811), Conus chaldaeus Röding 1798, С. ebraeus Linné, 1758, С. 
miliaris Hwass, 1792, С. nanus Broderip, 1833 et С. sponsalis Hwass, 1792. A 
l'exception de deux d'entre elles, Tectarius grandinatus et Conus nanus, toutes ces 
espèces peuvent être récoltées sur les récifs extérieurs de Raevavae où on note 
toutefois, comparativement aux Gambiers et à Fangataufa, la rareté de Turbo setosus 
dans la zone frontale du récif, de Conus sponsalis sur les platiers et de Littorina 
coccínea sur les blocs de la zone supérieure. En revanche, quelques espèces in- 
existantes ou inhabituelles sur les récifs extérieurs des Gambiers ou de Fangataufa sont 
bien représentées sur les platiers externes de Raevavae: Drupa elata, Cantharus 
undosus, Latirus nodatus, Peristernia nassatula et Nerita morio (voir Salvat, 1971). 

Rapa, par 27 ° 5 de latitude Sud, est en dehors de la zone intertropicale et la tem- 
pérature des eaux superficielles, si elle permet la croissance de certains coraux, ne 
conduit pas à la construction d'édifices récif aux importants; il n'y a ni récif frangeant, 



1 Egalement - Antenne de Tahiti B. P. 562, Papeete. 



^Recherches réalisées dans le cadre de conventions entre la DIR.C.E.N./S.M.C.B. et le Mu- 
séum de Paris. 

(429) 



430 PROC. FOURTH EUROP. MALAC. CONGR. 

ni récif barrière mais une pente littorale avec colonies coralliennes. La faune 
malacologique marine est considérablement plus pauvre qu'à Raevavae, 4 de latitude 
plus au Nord. Sur les 80 espèces de Mollusques testacês, Gastropodes et Bivalves, 
recensées dans cette dernière île, il ne nous a été donné de n'en retrouver que 10: 
Nerita plicata, Nerita morio, Drupa morum, D. ricinus, Morula granulata, Siphonaria 
sp., Modiolus auriculatus, Chama asper ella, Gafrarium pectinatum, Teilina rugosa. И 
convient de citer encore 6 espèces non récoltées à Raevavae mais par ailleurs 
communes dans les îles de la Société, des Gambiers, et des Tuamotu et qui doivent 
se trouver, selon toute vraisemblance, à Raevavae: Planaxis lineatus,Cerithium morus, 
Peristernia cf. sulcata, Malleus maculo sus , Crassostreacucullata et Cardita variegata. 
Signalons enfin 2 espèces du genre Patella en cours d'étude et 3 espèces que nous 
considérons présentement comme nouvelles, appartenant à deux familles: Turbinidae 
et Muricidae. Indiquons, de plus, la présence à Rapa d'un Polyplacophore et d'un 
Céphalopode octopode. Notre inventaire faunistique se ramène donc à 23 espèces 
malacologiques. 

On remarquera que sur 4 familles d'Archaéogastropodes représentées dans les îles 
de la Société, des Tuamotu et à Raevavae, trois possèdent des représentants à Rapa 
(Patellidae, Neritidae, Trochidae, absence de Turbinidae). Sur 6 familles de Méso- 
gastropodes (Littorinidae, Vermetidae, Cerithiidae, Strombidae, Cypraeidae, et 
Naticidae) une seule est encore représentée (Cerithiidae) 3 . Pour les Nêogastropodes, 
s'il existe à Rapa des Muricidae et des Mitridae, nous n'avons en revanche récolté 
aucune espèce de Buccinidae, de Conidae ou de Terebridae. 

Le substrat rocheux intertidal est dominé par les Patelles, les Polyplacophores et 
les Nerites et il présente des caractéristiques de zone tempérée avec notamment une 
couverture algale bien développée qui n'existe pas dans les îles aux latitudes plus 
faibles. Les quelques espèces de Muricidae {Drupa, Morula), très abondantes sur les 
récifs extérieurs d'îles plus septentrionales, n'existent à Rapa qu'en quelques localités 
où une plateforme de roche volcanique au niveau de la mer permet l'installation 
d'algues, notamment de Sargasses, recréant ainsi un biotope analogue à des récifs 
frangeants. 

ABSTRACT 

The littoral marine fauna of the Raevavae and Rapa islands of the Australs Archi- 
pelago south of Tahiti has been investigated. In the tropical Raevavae island the 
abundance of the fauna of the external reef is nearly similar to that found in the 
Society Islands or Tuamotu, the main difference being noted in the lagoon where a 
poorer fauna was found. On the other hand, in Rapa where no fringing reef nor outer 
barrier-reef are to be found, the fauna is much poorer, mainly in mollusks of which 
23 species only have been collected. 

BIBLIOGRAPHIE 

S AL VAT, В., 1970a, Etudes quantitatives sur les Mollusques récif aux de l'atoll de 

Fangataufa (Tuamotu, Polynésie). Cah. Pacif., 14: 1-57. 
SALVAT, В., 1970b, Les Mollusques des "récifs d'îlots" du récif barrière des îles 

Gambier (Polynésie). Bionomie et densités de peuplement. Bull. Mus. Hist. 

natur., Paris, 42, 3: 525-542. 
SALVAT, В., 1971, Mollusques lagunaires et récif aux de l'île de Raevavae (Australes, 

Polynésie). Malacol. Rev., 4: 1-15. 



Зипе ou 2 espèces de Cypraea seraient presentes que nous n'avons pas rencontrées. 



MALACOLOGIA, 1973, 14: 431-432 

PROC. FOURTH EUROP. MALAC. CONGR. 
SOME ASPECTS OF THE DISTRIBUTION OF THE MARINE MOLLUSCS OF WEST AFRICA 

J. Knudsen 

Zoological Museum, University of Copenhagen, Denmark 

ABSTRACT 

It is well known that the endemic West African fauna extends from a rather narrow border zone, beginning 
at about 15°N and fading off in the region between 10° and 20°S. A conspicuous element of the Mediter- 
ranean-Lusitanean fauna extends its range into the West African region. Most species seem to penetrate 
a relatively short distance south of the border zone just mentioned, while some are found throughout the 
entire West African region, thus being common to both regions. The proportion of Mediterranean-Lusitanean 
species in the northern part of the West African region may be put at 25-30%. 

A survey of Barnard's papers (1958-69) on the marine molluscs of South Africa shows that many earlier 
records of species occurring both in West andSouth Africa are erroneous, based on either misidentification 
or erroneous locality data. The number of well established cases of species occurring in both areas is 
very low. 

Thus the relations of the West African fauna to its 2 neighboring faunas are very different. This may to 
a great extent be explained in terms of larval ecology. Transport of pelagic larvae of molluscs from the 
Mediterranean-Lusitanean region to the West African is greatly facilitated through the Canary Current. 
On the other hand, the Benguela Current area with its low temperatures probably constitutes a major 
obstacle for an intrusion of larvae of benthic molluscs from the South African region (and the Pacific 
region), and possibly the Congo river's discharge of both fresh water and sediment adds to the effect. 

Less conspicuous fauna elements show aberrant distributional patterns: 1) Circumtropical (may not 
include East Pacific); 2) Circumtropical (may not include West Atlantic); 3) Amphi-Atlantic; 4) Indo- 
Pacific - West African, absent from South Africa. 

Many well studied examples of the above-mentioned categories can be found in the monographs published 
in "Johnsonia" and "Indo-Pacific Mollusca" and in other recent taxonomic works (Burgess, 1970; Fischer- 
Piette & Delmas, 1967; Turner, 1966). Veligers from 10 amphi -Atlantic species of prosobranchs were 
collected from the open ocean, and, thus, Scheltema (1971) was able to conclude that long-distance dis- 
persal of larvae takes place. By consulting a number of the recent monographs already referred to, I have 
found that distributional patterns of the above-mentioned 4 categories occurring in systematic groups not 
dealt with by Scheltema (I.e.) in many cases, may be explained by special means of spreading. Several 
species live attached to mangrove or other plant material or bore into wood. Such forms may easily be 
transported with the oceanic current systems. Several cases are obviously misidentifications or they 
belong to "critical" taxonomic groups which have not been subjected to recent study on a world wide or 
oceanic scale. 

Scheltema (I.e.) states that frequent long-distance dispersal of larvae may facilitate the gene flow between 
widely separated populations, and that the degree of morphological differentiation between eastern and 
western Atlantic populations of gastropod species having amphi -Atlantic distributions would be expected 
to bear an inverse relationship to the frequency with which the larvae of these species were found in the 
open sea. On consulting the above-mentioned papers it seems quite obvious that populations on both sides 
of the Atlantic are conspecific while in other cases morphological differences at the specific or the sub- 
specific level are found. 

Differences at the subspecific level may be found between populations in the Indo-Pacific and the East 
Atlantic. A few examples may be mentioned: Littorina scabra scabra (Linnaeus, 1758) is widely distributed 
in thelndo-West Pacific region, while the subspecies L. s. angulifera (Lamarck, 1822) occurs in morpholo- 
gically identical populations on both sides of the Atlantic (Rosewater, 1970). Dosinia exoleta exoleta (Lin- 
naeus, 1758) is distributed in the East Atlantic from about 68°N to off the Congo. Dosiniae.amphidesmoid.es 
(Reeve, 1850) is an Indo-West Pacific subspecies (Fischer-Piette & Delmas, I.e.). Future taxonomic 
revisions may reveal many similar examples. 

The West African region may be subdivided into 3 zones (Williams, 1968): 1) western tropical zone 
(from about 11° N to Cape Palmas, about 8°W; 2) central upwelling zone (from Cape Palmas to the region 
west of Lagos, about 3°E); and 3) eastern tropical zone (from west of Lagos to Cape Lopez, about 1°S). 
The zones north and south of these 3 are termed north transitional and south transitional zone, respec- 
tively. 

The 2 tropical zones are characterized by having surface temperatures always exceeding 24°C, with 
rather small seasonal fluctuations. The upwelling zone has temperatures showing considerable annual 
fluctuations (up to 10°C). 

The distribution of some species may be explained by the differences in environmental conditions 
prevailing in these zones. Thus Burgess (I.e.) records 4 species of Cypraea restricted to the western 
tropical zone, and the distribution of some species of Marginella shows the same pattern. There are also 
examples of species apparently being confined to the eastern tropical zone. 



(431) 



432 PROC. FOURTH EUROP. MALAC. CONGR. 

REFERENCES 

BARNARD, K. H., 1958-69, Contributions to the knowledge of South African marine mollusca. Part I 
(1958), Ann. S. Afr. Mus., 44: 73-163; Part II (1959), ibid., 45: 1-237; Part III (1963), ibid., 47: 1-199; 
Part IV (1963), ibid., 47: 201-360; Part V (1964), ibid., 47: 361-593; Part VI (1969), ibid., 47: 595-661. 

BURGESS, С M., 1970, The living cowries. New York, 389 p. 

FISCHER-PIETTE, E. & DELMAS, D., 1967, Revision des Mollusques Lamellibranches du Genre Dosinia 
Scopoli. Mém. Mus. natn. Hist, natur., Paris. Nouv. Ser. Sér. A, Zool., 47(1): 1-91. 

ROSEWATER, J., 1970, The family Littorinidae in thelndo-Pacific. Indo-Pacific Mollusca, 2(11): 417-506. 

SCHELTEMA, R. S., 1971, Larval dispersal as a means of genetic exchange between geographically sepa- 
rated populations of shallow-water benthic marine gastropods. Biol. Bull., 140: 284-322. 

TURNER, R. D., 1966, A survey and illustrated catalogue of the Teredinidae (Mollusca: Bivalvia). Cam- 
bridge, Mass., 265 p. 

WILLIAMS, F., 1968, General Report. Report on the Guiñean trawling survey. 1. Lagos, 828 p. 



MALACOLOGIA, 1973, 14: 432 

PROC. FOURTH EUROP. MALAC. CONGR. 

LES MOLLUSQUES BATHYALS DU GOLFE DE TARENTE 

Pietro Panetta 

Istituto Sperimentale Talas sograf ico Taranto, Via Roma 3 
/-74100 Taranto, Italie 

RESUME 

L'Albatros, dans les années 1966-1969, a effectué 9 croisières dans le golfe de Tárente, en prélevant 
500 échantillons dans l'espace compris entre la côte et 35 milles au large. La zone bathyale, comprise 
entre 200-1000 m, est assez restreinte le long de la côte salentine, tandis qu'elle est assez étendue le 
long de la côte calabraise. On peut remarquer une alternance de fonds boueux et vaseux, ceux-ci formant 
une grande extension jusqu'aux grandes profondeurs. 

La faune est très dispersée, pauvre en espèces avec prédominance de Polychètes; elle est caractérisée 
par une association de Cyclammina cancellata et de Nassa limata Chemn., Bullaria utricula (Brocchi), 
Nucula tenuis aegeensis (Fbs.), Abra alba (Wood), Lissactoeon exilis Fbs., Trophonopsis carinata (Biv.) 
et T. richardi (Dautz. & Fisc). A partir de 400-500 m, on peut remarquer beaucoup de coquilles de 
Ptêropodes: Cavolinia tridentata Forsk., C. trispinosa Les., Cleodora pyramidata Les. et Styliola recta 
Les. De nombreuses espèces rares de Mollusques ont été découvertes: Malletia obtusa (Sars), Cuspidaria 
costellata (Des.), Pleurotomella pycnoides (Dautz. & Fisc), Pleurotoma macro (Watson) et Pleurotomella 
bairdi Verril & Smith. 

La faune malacologique bathyale du golfe de Tarente est une faune atlantique très pauvre qualitativement. 
Les espèces sont pour la plupart euribathyales, mais il y a aussi des abyssales. 



MALACOLOGIA, 1973, 14: 433-437 

PROC. FOURTH EUROP. MA LAC. CONGR. 

QUELQUES CAS DE DIPHYOIDIE OBSERVES SUR DES 
MOLLUSQUES CONTINENTAUX 1 

Louis Chaix 

Département d'Anthropologie, Université de Genève, Suisse 

Une coquille affectée du phénomène de diphyoidie montre une tendance à une scission 
transverse et médiane de son test (Fig. 1). Certains mollusques fossiles montrent 
cette morphologie particulière en tant que caractère spécifique comme certains 
Gastéropodes du Trias (Emarginula) ou actuels comme Seis sure lia. Il est à remarquer 
que cette échancrure présente des dimensions très variables. Plusieurs Brachiopodes 
fossiles sont également diphyoides, les plus caractéristiques étant Eospirifer du 
Silurien et Dictyothyris du Jurassique. Il est à remarquer que sur les gastéropodes 
et les brachiopodes cités, on ne peut pas parler de position de la scissure transverse 
et médiane, puisqu'elle est longitudinale, le test de ces mollusques étant assimilable 
à une valve. En étudiant les tests de certains mollusques continentaux dulcicoles, 
Lamellibranches et Gastéropodes, nous avons constaté des caractères morphologiques 
rappelant cette diphyoidie. La plupart de nos observations ont été faites sur de petits 
Lamellibranches du genre Pisidium, provenant de sondages dans les sédiments post- 
glaciaires du Bassin Lémanique. De nombreuses valves présentent une ébauche de 
scissure plus ou moins développée dans la partie médiane de la coquille (Fig. 2). Ce 
sillon peut être faible ou assez profond et se retrouver sur la face interne de la valve. 
Dans d'autres cas, il se réduit à un lacis de rainures sinueuses, mais dont le sommet 
occupe toujours une position médiane (Fig. 3). Ce sillon peut être limité au bord de 
la coquille ou s'étendre très haut dans la région du crochet. Un fait qui nous a paru 
important, c'est la position médiane de cette échancrure, quel que soit son degrê c La 
majorité des cas observés se rapporte aux espèces Pisidium nitidum Jen. et Pisidium 
milium Held. Sur quelques exemplaires complets conservés dans la craie lacustre, 
nous avons pu voir que cette diphyoidie affectait les deux valves d'une manière absolu- 
ment symétrique. Notre matériel provenait de sondages à but palêontologique et 
nous avons jugé utile de calculer le pourcentage d'individus diphyoides d'un échantillon 
à l'autre. Sur le graphique suivant (Fig. 4) on peut voir, replacée dans un cadre 
chronologique, cette évolution du phénomène. Nous avons également observé cette 





FIG. 1. Une coquille affectée du phénomène de diphyoidie montre une tendance à une scission 
transverse et médiane de son test. 



*A la mémoire du Professeur Ad. Jayet. 

(433) 



434 



PROC. FOURTH EUROP. MALAC. CONGR. 





Pisidium nitidum Jen, 





Pisidiun milium Held, 





, 1mm 



Pisidium nitidum Jen 



FIG. 2. En haut: Pisidium nitidum Jen. ; en bas: Pisidium milium Held. 
FIG. 3. Pisidium nitidum Jen. 



CHAIX 



435 



Ech . 




Total 


i 

N.diph. 


% diph. 


Ech. 


Total 


N .diph. 


% diph. 


I 


I 








17 


152 


16 . 


10,5 


2 


I 








18 


151 


24 


15,8 


3 


II 








19 


143 


13 


9,1 


4 


2 








20 


156 


II 


7,0 


5 


7 


2 


28,5 


21 


157 


10 


6,3 


6 


120 


о 


С 


22 


225 


19 


8,4 


7 


65 


7 


10,7 


23 


213 


II 


5 ,1 


8 


73 


4 


5,4 


24 


33 


5 


15,1 


9 


144 


17 


11,9 


25 


I 


^0 





10 


95 


18 


18,9 


26 











II 


281 


48 


17 ,0 


27 


136 


4 


2,9 


12 


247 


44 


17, 7 


28 


192 


2 


1,0 


13 


133 


30 


22,5 


29 


66 








14 


77 


7 


9,0 


30 


114 








15 


156 


46 


29,5 


31 


I 








16 


177 


6 


3,3 


32 


18 


I 


5,5 




FIGURE 4 



436 



CHAIX 



1 
cm. 





FIG. 5. Radix auricularia L. 

diphyoidie sur un gastéropode actuel du Rhône, Radix auricularia (L.). Ici, comme nous 
l'avons fait remarquer plus haut, le sillon est longitudinal et correspond à un certain 
rebroussement des stries d'accroissement (Fig. 5). On remarquera également la 
position médiane de l'échancrure du labre. 

Plusieurs auteurs ont tenté d'expliquer ce phénomène. Certains, comme Bourguignat, 
ont fait une espèce de ces individus diphyoides sous le nom de Pisidium sinuatum. 
Nous avons aussi remarqué dans certaines collections de musées des exemplaires 
d'Unionidés présentant cette particularité et portant des noms spécifiques tels que 
Urdo sinuata Lam. ou Unio sinatus Lam. et provenant de la Loire ou de la Garonne. 
J. Favre, en 1927, a signalé certains individus de Lymnaea stagnalis possédant des 
incisions plus ou moins développées du bord palléal. Geyer a évoqué une action de 
lacération mécanique du manteau et d'autres auteurs (Mermod, 1930) ont signalé la 
présence d'une grande quantité de cercaires. Mais tous ces faits ont été constatés 
dans de très faibles proportions (1 ou 2%), alors que les calculs que nous avons 
effectué sur le produit de nos sondages montrent de forts pourcentages, jusqu'à 29,5% 
de diphyoides. Nous pensons que l'hypothèse d'une lacération mécanique si localisée 
est à rejeter. La position toujours semblable de l'échancrure nous semble avoir 
une autre origine. L'attribution spécifique différente donnée à de tels individus nous 
semble également arbitraire, la diphyoidie pouvant apparaître sur des mollusques de 
genres différents. L'influence des divers paramètres du milieu mériterait une étude 
approfondie de même qu'une approche génétique du problème. Kuijper nous signalait 
récemment qu'il n'avait jamais observé cette diphyoidie sur les embryons de Pisidium, 
et d'autres observations signalent que l'échancrure des gastéropodes du genre Scis- 
surella n'apparait que chez les individus adultes. Seule une étude biologique pourrait 
apporter une solution au problème que nous nous sommes posé face au nombre 
important de Pisidium aberrants des niveaux post-glaciaires que nous avons étudiés. 

SUMMARY 



Diphyoidy is a morphological character affecting the mollusc's shell. The diphyoidie 
shell shows a transversal furrow in the mesial part of the valve. We have observed a 
similar fact on fossil lamellibranchs from borings through post-glacial deposits in 
the Lemanic area. The species concerned are Pisidium nitidum Jen. and Pisidium 
milium Held. The shell shows a mesial furrow more or less developed, alone or 



PROC. FOURTH EUROP. MALAC. CONGR. 437 

forming a network of grooves; we must remark that the point of junction of these 
grooves is always mesial. A similar observation was made on a recent living 
species of lymnaeid (Radix auricularia L.). We have computed the percentages of 
diphyoides during the post-glacial times. At present, no explication can be advanced 
for the diphyoidy. Some authors have made new species with diphyoid molluscs, 
like Bourguignat with Pisidium sinuatum, and we have seen in collections unionids 
named Unio sinuata Lam. or Unio sinat